Story highlights Schumer said the need for a special prosecutor was stronger after Trump fired Comey 
 
 The senator again called for Sessions to step down as attorney general 
 
 Schumer also has requested an IG investigation into any interference in the Russia probe 
 
 He called for public testimony from Comey 
 
 Washington (CNN) Senate Minority Leader Chuck Schumer said Sunday that the Senate should refuse to confirm a new FBI director until the Department of Justice appoints a special counsel to lead a probe into allegations of collusion between the Trump campaign and Russia. 
 
 "I think there are a lot of Democrats who feel that way," Schumer said on CNN's "State of the Union." "We'll have to discuss it as a caucus, but I would support that move." 
 
 Virginia Sen. Mark Warner, the top Democrat on the Senate intelligence committee, proposed the idea after President Donald Trump fired FBI Director James Comey last week. 
 
 Trump has yet to name his choice to replace Comey, for which interviews have taken place this weekend , and the Justice Department thus far has declined to appoint a special prosecutor. Republicans leading Congress have also declined to compel a special prosecutor or create an independent investigative commission. 
 
 Acknowledging Democrats' limited influence in Congress, Schumer told anchor Jake Tapper, "The key here, of course, is getting some of our Republican colleagues to join us." 
 
 Read More ||||| Washington (CNN) Former Director of National Intelligence James Clapper said Sunday that he thinks US institutions are under assault from President Donald Trump. 
 
 "I think in many ways our institutions are under assault both externally -- and that's the big news here is the Russian interference in our election system -- and I think as well our institutions are under assault internally," Clapper told anchor Jake Tapper on CNN's "State of the Union." 
 
 Pressed if he meant US institutions were under assault internally from the President, Clapper responded, "Exactly." 
 
 Clapper called on the other branches of the federal government to step up in their roles as a check on the executive. 
 
 "The founding fathers, in their genius, created a system of three co-equal branches of government and a built-in system of checks and balances," Clapper said. "I feel as though that is under assault and is eroding." 
 
 Democrats and several Republicans in Congress have publicly mulled pressing the Department of Justice to appoint a special prosecutor or establishing an independent investigative body that could look into allegations of potential collusion between Russia and the Trump campaign in what the US intelligence community says was Moscow's efforts to influence the US election. 
 
 The Senate must confirm a new FBI director once Trump names a candidate; that FBI director will take a lead role in the Russia investigation. 
 
 Utah Republican Sen. Mike Lee advocated on "Fox News Sunday" that Trump appoint Judge Merrick Garland to head the FBI. Josh Holmes, a former aide to Senate Majority Leader Mitch McConnell, said later on the program that the Republican leader had just called him to say he would support Garland for FBI's top spot. 
 
 Garland was President Barack Obama's pick to replace Supreme Court Justice Antonin Scalia after Scalia's death last year. If appointed and confirmed as FBI director, Garland's appointment would create a vacancy on the US Circuit Court of Appeals for the District of Columbia, which has jurisdiction over the DC area and federal agencies, making it one of the highest legal authorities in the country short of the Supreme Court. 
 
 Can't refute or confirm collusion questions 
 
 Clapper also said Sunday that the President and the White House are wrong to cite Clapper's previous Senate testimony on the questions about alleged collusion between the Trump campaign and Russia as proof that no such collusion exists, emphasizing that no one should portray his comments as "exculpatory" -- something Trump has done repeatedly on Twitter. 
 
 Director Clapper reiterated what everybody, including the fake media already knows- there is "no evidence" of collusion w/ Russia and Trump. — Donald J. Trump (@realDonaldTrump) May 8, 2017 
 
 When James Clapper himself, and virtually everyone else with knowledge of the witch hunt, says there is no collusion, when does it end? — Donald J. Trump (@realDonaldTrump) May 12, 2017 
 
 "The bottom line is I don't know if there was collusion, political collusion," Clapper told Tapper. "I don't know of any evidence to it. So I can't refute it, and I can't confirm it." 
 
 Clapper told NBC in March that he didn't know of any evidence that demonstrated collusion between Russia and the Trump campaign. At a Senate Judiciary subcommittee hearing earlier this month, Clapper clarified that statement, saying he was also unaware of the FBI's investigation into the matter until Comey made it public in March. 
 
 At that subcommittee hearing, former acting Attorney General Sally Yates, whom Trump fired in January for refusing to defend his initial temporary ban on visitors from several Muslim-majority countries and suspension of the entry of Syrian refugees, declined to answer the question of whether there was evidence of collusion publicly; in her answer, she also noted that Clapper had been unaware of the FBI investigation. 
 
 Clapper said Sunday that his "standard practice" as the leader of the intelligence community during the Obama administration was to defer to the FBI on any counterintelligence investigations. 
 
 He noted the intelligence community's joint assessment declaring Russia had interfered in the 2016 election did not contain any reporting about political collusion. 
 
 "I did not have any evidence," Clapper said, again noting he was unaware of the executive branch investigation into allegations of collusion. 
 
 Comey and Trump 
 
 On Friday, Trump raised eyebrows by tweeting a warning to Comey, whom he fired unexpectedly on Tuesday, about leaking information to the media, saying he "better hope that there are no 'tapes' of our conversations before he starts leaking to the press." 
 
 In his news briefing later that day, White House press secretary Sean Spicer declined repeatedly to explain what the tweet meant or address questions about whether there were recording devices in the Oval Office. 
 
 James Comey better hope that there are no "tapes" of our conversations before he starts leaking to the press! — Donald J. Trump (@realDonaldTrump) May 12, 2017 
 
 Trump and Comey had a private dinner in the White House on January 27 in which a source close to Comey said the President asked the FBI director to pledge his loyalty, which Comey, who reportedly was taken aback by the request, refused to do. 
 
 The dinner was on the same day that Yates went to the White House to warn the administration about since-ousted national security adviser Michael Flynn's potential vulnerability to Russian blackmail and that Trump issued the executive order restricting travel from several majority-Muslim nations. 
 
 Clapper said Sunday that he spoke with Comey prior to the dinner while at an event at FBI headquarters in Washington. 
 
 "He mentioned to me the invitation he had from the President for dinner," Clapper said. "He was -- my characterization -- uneasy with it both from the standpoint of the optic of compromising his independence and the independence of the FBI." ||||| President Donald Trump gestures after speaking to members of the media aboard Air Force One before his departure from Andrews Air Force Base, Md., Saturday, May 13, 2017. Trump is traveling to Lynchburg,... (Associated Press) 
 
 WASHINGTON (AP) — Former Director of National Intelligence James Clapper on Sunday described a U.S. government "under assault" after President Donald Trump's controversial decision to fire FBI director James Comey, as lawmakers urged the president to select a new FBI director free of any political stigma. 
 
 "I think, in many ways, our institutions are under assault, both externally -- and that's the big news here, is the Russian interference in our election system," Clapper said. "I think as well our institutions are under assault internally." 
 
 When he was asked, "Internally, from the president?" Clapper said, "Exactly." 
 
 Clapper spoke following Trump's sudden firing of Comey last week, which drew sharp criticism because it came amid the FBI's probe into Russia meddling in the 2016 presidential election and possible ties between Russia and the Trump presidential campaign. 
 
 Clapper said America's founding fathers had created three co-equal branches of government with checks and balances, but with Trump as president, that was now "under assault and is eroding." 
 
 Lawmakers from both parties also criticized Trump's actions last week, which included changing explanations from the White House for the firing and an ominous tweet by Trump that warned Comey against leaks to the press because he may have "tapes" of their conversations. The lawmakers urged the president to select a new FBI director without any political background. 
 
 Republican Sen. Lindsey Graham, a member of the Judiciary Committee, said promoting an FBI agent to lead the agency would allow the nation to "reset." He dismissed as less desirable at least two of the 14 candidates under consideration by Trump, former Rep. Mike Rogers of Michigan and Sen. John Cornyn of Texas, explaining that "these are not normal circumstances." 
 
 Rogers, an ex-FBI agent and former chairman of the House Intelligence Committee, has drawn the backing of the FBI Agents Association. Cornyn is the No. 2 Republican in the Senate. 
 
 "It's now time to pick somebody who comes from within the ranks, or is of such a reputation who has no political background at all who can go into the job from Day 1," the South Carolina Republican said. Asked whether Rogers or Cornyn would be good choices, Graham flatly said, "no." 
 
 "The president has a chance to clean up the mess he mostly created," Graham said, adding, "I have no evidence the president colluded with the Russians at all, but we don't know all the evidence yet." 
 
 Senate Minority Leader Chuck Schumer of New York said the new FBI director should certainly be someone "not of partisan background" with "great experience" and "courage." He left open the possibility that Democrats might try and withdraw support for a new FBI director unless the Justice Department names a special prosecutor. Under rules of the Senate, Republicans could still confirm an FBI director with 51 votes. Republicans hold 52 seats in the chamber to Democrats' 48. 
 
 Less than a week after Trump fired Comey, the administration has interviewed at least eight candidates to be FBI director, and Trump has said a decision could come before he leaves Friday on his first overseas trip as president. 
 
 "I think the process is going to go quickly. Almost all of them are very well-known," Trump said of the candidates before Air Force One took off for Lynchburg, Virginia, where he gave the commencement address at Liberty University. "They've been vetted over their lifetime essentially, but very well-known, highly respected, really talented people. And that's what we want for the FBI." 
 
 Trump abruptly fired Comey on Tuesday and later said Comey was a "showboat" and "grandstander" who was not doing a good job. The firing drew a wave of criticism in large part because the FBI has been investigating whether election meddling by Russia involved people in Trump's presidential campaign, and Trump said in an interview with NBC that the investigation factored into his decision to fire Comey. The changing rationales the White House offered added an element of chaos to the president's action. 
 
 The FBI director serves a 10-year term but can be replaced by the president. 
 
 So far 14 people — lawmakers, attorneys and law enforcement officials among them — have emerged as candidates. Eight met at the Justice Department on Saturday with Attorney General Jeff Sessions and his deputy, Rod Rosenstein. 
 
 The first candidate to arrive for interviews was Alice Fisher, a high-ranking Justice Department official in the George W. Bush administration. 
 
 Also interviewed were: 
 
 —Adam Lee, special agent in charge of the FBI's office in Richmond, Virginia. 
 
 — Andrew McCabe, the acting FBI director. 
 
 —Michael J. Garcia, a former prosecutor and associate judge on New York's highest court. 
 
 —Cornyn, a former Texas attorney general. 
 
 —U.S. District Judge Henry E. Hudson, a Bush appointee who struck down the centerpiece of the Obama administration's health care law in 2010. 
 
 —Frances Townsend, a former Bush homeland security and counterterrorism adviser. 
 
 —Rogers. The FBI Agents Association says it believes his diverse background makes him the best choice. 
 
 Fisher and Townsend were the only women on the list of candidates. The FBI has never had a female director. 
 
 Sessions has faced questions over whether his involvement in Comey's firing violates his pledge to recuse himself from investigations into Russian interference in the election. Some lawmakers have alleged the firing was an effort to stifle that FBI probe. 
 
 Justice Department spokeswoman Sarah Isgur Flores said Sessions and Rosenstein were involved in the interviews because the FBI director reports to them as attorney general and deputy attorney general. 
 
 Clapper and Schumer made their comments on CNN's "State of the Union"; Graham spoke on NBC's "Meet the Press." 
 
 ___ 
 
 Associated Press writers Sadie Gurman and Darlene Superville contributed to this report. ||||| Sen. Mark Warner Mark WarnerElection hacking fears turn heat on Homeland Security Are Democrats trying to pin the blame for their own sins on Russia? Policymakers forget duty to protect taxpayers from financial failures MORE (D-Va.), the vice chairman of the Senate Intelligence Committee on Sunday said the committee would “love” to have former FBI Director James Comey testify in an open hearing. 
 
 “I think Jim Comey deserves his chance to lay out to the American public his side of the facts," Warner told ABC’s “This Week." 
 
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 “We would love to have Director Comey appear in an open hearing,” Warner said when asked if the committee has invited Comey to testify publicly since his firing last week. 
 
 While Comey declined to testify in a closed door hearing, the former FBI head is reportedly willing to testify in an open hearing. 
 
 The Senate Intelligence Committee has oversight on the probe into Russia’s meddling in the United States election, which was led by Comey at the FBI. The investigation also includes looking into any potential ties between Trump campaign staff members and Russia. 
 
 Comey was fired last week by Trump in a signed letter calling for “a new beginning” at the FBI. 
 
 The Trump administration has provided various reasons for Comey’s dismissal, including recommendations from the Justice Department and Trump’s own statement that Comey “was not doing a good job.” 
 
 “How he was treated was pretty awful by this president," Warner said of Comey on Sunday.
– The former director of national intelligence minced no words Sunday in describing "our institutions" as being "under assault, both externally—and that's the big news here, is the Russian interference in our election system," Clapper told CNN in addressing James Comey's firing as he investigated that interference. "I think as well our institutions are under assault internally." Asked, "Internally, from the president?" Clapper said, "Exactly." He continued: "The founding fathers, in their genius, created a system of three co-equal branches of government and a built-in system of checks and balances. I feel as though that is under assault and is eroding." There was lots more Comey reaction on the Sunday dial, via the AP: Chuck Schumer: Wants a new FBI director "not of partisan background" with "great experience" and "courage." He also said Democrats should refuse to confirm a new director until a special investigator into Russian meddling had been appointed, per CNN. Lindsey Graham: "It's now time to pick somebody (to run the FBI) who comes from within the ranks, or is of such a reputation who has no political background at all who can go into the job from Day 1." Mark Warner: "I think Jim Comey deserves his chance to lay out to the American public his side of the facts," Warner said, per the Hill. "We would love to have Director Comey appear in an open hearing." Further, "how he was treated was pretty awful by this president."