The White House and top Republicans rejected calls for a special prosecutor to probe allegations that Mr Donald Trump's campaign colluded with Russia, despite a firestorm over the US President's abrupt sacking of Federal Bureau of Investigation (FBI) director James Comey.
As the search for Mr Comey's replacement began, Mr Trump lashed out at opposition Democrats who angrily accused the President of removing him because the FBI was intensifying its probe into suspected Kremlin interference in last year's presidential election.
But yesterday, the FBI's acting director Andrew McCabe said his agency would continue looking into possible links between Russia and the 2016 Trump campaign under questioning from the Senate Intelligence Committee.
He also promised to tell the committee if there was any effort to interfere with the probe.
"You cannot stop the men and women of the FBI from doing the right thing," he said, two days after his boss was fired.
Mr McCabe also contradicted White House assertions that the agency's rank-and-file had lost confidence in Mr Comey. "I can tell you director Comey enjoyed broad support in the FBI and still does to this day," he said.
Separately, the committee has issued a subpoena for Mr Trump's former national security adviser Michael Flynn, requesting "documents relevant to the committee's investigation into Russian interference with the 2016 election".
The ousted FBI director himself has been summoned to appear before the Senate committee in a closed door hearing next Tuesday.
Yesterday, Democrats continued to call for an independent prosecutor or special counsel - a method not used since 1999 - to probe alleged Russian links with key Trump campaign staff, to determine whether there was collusion to damage Mr Trump's rival Hillary Clinton. They questioned the reasons given for Mr Comey's firing - his handling of the FBI's probe into Mrs Clinton's handling of classified e-mails.
"Was this really about something else?" Democratic Senator Chuck Schumer said in the Senate, adding: "Nothing less is at stake than the American people's faith in our criminal justice system and the integrity of the executive branch of our government."
The President lambasted the Democrats, tweeting: "Dems have been complaining for months & months about Dir. Comey. Now that he has been fired they PRETEND to be aggrieved. Phony hypocrites!"
Attorney-General Jeff Sessions and Deputy Attorney-General Rod Rosenstein, who played a key role in setting up the Comey dismissal, have begun interviewing candidates for FBI interim director.
The list reportedly includes deputy director McCabe; former New York City police commissioner Ray Kelly; FBI special agent in charge of its Chicago division Michael Anderson; executive assistant director for Criminal, Cyber, Response and Services at the FBI Paul Abbate; special agent in charge of the FBI's Richmond Division Adam Lee, and head of counterintelligence for the US government William Evanina.
Outlier candidates who may be picked for their loyalty to Mr Trump include former New York mayor Rudy Giuliani and New Jersey governor Chris Christie.
But they may face rough weather in confirmation hearings, including from some Republicans uneasy over the firing of the FBI director.
Senator John McCain told CNN: "I don't think that (Mr Comey's mishandling of the e-mail probe) is sufficient rationale (for his firing)."
Intelligence Committee chairman Richard Burr, Foreign Relations Committee chairman Bob Corker, and senators Ben Sasse of Nebraska and Jeff Flake of Arizona have all expressed concern.
But Senate majority leader Mitch McConnell dismissed calls for an independent prosecutor, while White House deputy spokesman Sarah Huckabee Sanders said: "We don't think it's necessary. You've got a House committee, a Senate committee, and the Department of Justice all working on this."