 here president biden's campaign manager says when biden comes out of isolation due to covid he could hit the campaign trail next week that as cbs's ed o'keefe reports three more senators have joined the growing chorus calling on biden to drop out new mexico senator martin heinrich says it's in the best interest of our country for the president to go and montana's john tester says if the president steps aside the party should have an open contest for the nomination not just handed to vice president harris