President Donald Trump has contradicted the White House line on his reason for dismissing FBI boss James Comey, who he called a “showboat” and a “grandstander”.

President Trump told US broadcaster NBC on Friday morning (AEST) he was always going to fire the FBI director, regardless of advice from the Attorney General and Deputy Attorney General.

The FBI chief’s dismissal came as he was leading an investigation into possible Russian interference in the 2016 US presidential election and possible collusion between the Trump campaign and Moscow.

The President’s shift on previous statements that he acted on advice from his top legal appointees comes as Mr Comey’s replacement praised his former boss to the US Senate, saying he had “broad support” within the FBI.

“He’s a showboat. He’s a grandstander. The FBI has been in turmoil,” President Trump told NBC in his first interview since his abrupt firing of Mr Comey.

“I was going to fire Comey. My decision,” the President said. “I was going to fire regardless of recommendation.”

The Senate Intelligence Committee has vowed to press ahead with its investigation into the alleged Russian election meddling as aggressively as possible despite turmoil over the Mr Comey’s dismissal.

Reaction in Washington to Mr Comey’s firing Wednesday was ferocious and bipartisan.

Democrats denounced the move, likening it to the “Saturday Night Massacre” of 1973 in which President Nixon fired an independent special prosecutor investigating the Watergate scandal.

Comey enjoyed ‘broad support’

Acting FBI director Andrew McCabe, meanwhile, has contradicted key White House statements on his predecessor’s sacking, saying Mr Comey enjoyed broad support within the FBI.

Mr McCabe also asserted that the Russia probe was a “highly significant investigation,” in direct contradiction to earlier White House statements that downplayed its significance.

Acting FBI director Andrew McCabe contradicted key White House assertions. Photo Getty

White House deputy press secretary Sarah Huckabee Sanders on Wednesday said the Russia investigation was “probably one of the smallest things” that the FBI has “got going on their plate”. 

Mr McCabe told the Senate committee he would not describe the investigation that way.

President Trump reasserted to NBC that Mr Comey had told him he was not part of the Russia probe, saying the then-FBI director told him three times he was not under investigation.

Mr McCabe, however, told the Senate committee it was not standard practice to inform someone that they were not a target.

The acting FBI director also contradicted President Trump’s claim that Mr Comey had lost the support of rank-and-file members of the bureau, an assertion used to justify his firing.

Mr McCabe said that claim was not accurate and that Mr Comey “enjoyed broad support” within the agency and he personally held Mr Comey in the “absolute highest regard.”

He said it was the “greatest privilege” of his career to serve under him.

McCabe was made acting director on Tuesday evening following the firing of Comey. Justice Department leaders are interviewing other contenders for the position.

Voter fraud commission

– With agencies