WASHINGTON (Reuters) - Hillary Clinton has distanced herself from President Barack Obama on a number of high-profile issues since starting her bid for the White House. Now, under pressure from left-leaning challenger Bernie Sanders, she is embracing him and his legacy with fervor. That strategy could pose problems for Clinton in the long run as Republicans look for fodder to portray her as representing Obama’s third term should she win the Democratic nomination. As she faces an unexpected challenge from Sanders in the early voting states, Clinton’s move to portray herself as an heir to Obama’s policies is aimed at courting young voters and progressives who are part of the president’s political base.  But she could be setting herself up for difficulties with a general electorate weary of the status quo. Over and over again during a tense Democratic presidential debate on Sunday, Clinton, who served as Obama’s secretary of state for four years, played up her ties to the president and accused Sanders of undermining him. Gone were her mentions of differences with the president over Syria, trade, and immigration. Instead, Clinton praised the Affordable Care Act, Obama’s signature healthcare law. She highlighted her connection to the administration’s Iran nuclear deal and lauded the White House for sending staff to Silicon Valley to discuss cybersecurity. Clinton, who ran against Obama for the 2008 Democratic nomination and then joined his administration, said she could accept Sanders’ criticism of her campaign donations - one of the Vermont senator’s favorite critiques - but wouldn’t tolerate similar criticism targeted at her former boss. “The comments that Senator Sanders has made ... don’t just affect me, I can take that, but he’s criticized President Obama for taking donations from Wall Street. And President Obama has led our country out of the Great Recession,” she said. “I’m going to defend President Obama for taking on Wall Street, taking on the financial industry, and getting results.” Clinton played up her service as his top diplomat, emphasized her hours advising him in the Situation Room, and accused Sanders of wanting to throw out Obamacare, all while debating in South Carolina, a state in which Obama is well liked. Republicans welcomed the opening Clinton provided for them to cast her White House run as a bid for a third Obama term. “When you have a president who is so unpopular as President Barack Obama ... and his chief diplomat is embracing those policies and running as his third term, it’s going to be next to impossible,” said Ric Grenell, a former U.S. spokesman at the United Nations under Republican President George W. Bush.  Dissatisfaction with Obama and the agenda in Washington have helped propel two candidates outside the Republican establishment - businessman Donald Trump and Senator Ted Cruz of Texas - to the top of the party’s crowded presidential field. Trump appeared to reference Clinton’s comments about the president’s policies in a speech at Liberty University on Monday, saying the country cannot afford another four years of the same thing. “We can’t have another four years of Barack Obama,” he said. “We can’t have another four years of Hillary Clinton.” Perhaps foreshadowing future ads, the Republican National Committee noted that Democrats at Sunday’s debate had backed the current occupant of the White House. “Not content with Barack Obama’s legacy of a toxic Iran deal and the rise of ISIS in the Middle East, Democrats doubled down on the extreme and failed policies of the current administration,” the RNC said in a statement. Democrats said Clinton was embracing Obama because he is popular with the party’s base, including in Iowa, which holds the first nominating contest, called a caucus, on Feb. 1. “It just makes sense to highlight where you agree with a president who is popular among caucus goers, and Secretary Clinton found ways to get that done,” said Brent Colburn, a former Obama administration official who served as communications director for his 2012 campaign. Democratic strategist Richard Socarides, a Clinton supporter, said Republicans were bound to portray her potential presidency as a third Obama term anyway.  “She deserves a lot of credit for putting the country first and going to work for him,” Socarides said. “After Iowa and New Hampshire especially, that will matter to a lot of Democratic primary voters. And she is right to point out that Bernie has not always been there. She has.”      (Additional reporting by Alana Wise and Sarah N. Lynch; Editing by Caren Bohan, Mary Milliken and Marguerita Choy) SAP is the sponsor of this coverage which is independently produced by the staff of Reuters News Agency.