As the White House scrambled to defend the apparently hastily-planned decision of the president to fire FBI Director James Comey, Democrats insisted the only just course of action was to appoint a special prosecutor. Republicans immediately said they would not agree to such a move.

With the shock from Mr Trump’s move still reverberating, the Democratic leader in the Senate, Chuck Schumer, called on the same Trump administration official who had recommended Mr Comey’s ousting, to now appoint a special investigator.

Mr Schumer said Rod Rosenstein, the deputy attorney general, had the power to take such a step. Speaking in the Senate, the senator called on Mr Rosenstein to do so.

“Mr Rosenstein has the authority to appoint a special prosecutor right now. He needs no congressional authorisation. This would simply be a step that he could take,” he said.

He added: “A special prosecutor is not subject to day-to-day supervision by the Attorney General or anyone else at the Justice Department. That means the special prosecutor would have much greater latitude in who he can subpoena, which questions they ask, how to conduct an investigation.”

His Republican counterpart, majority leader Mitch McConnell, said Republicans would not agree, saying it would interfere with the work already done by the Senate Intelligence Committee.

“Today we’ll no doubt hear calls for a new investigation which could only serve to impede the current work being done,” Mr McConnell said. “Partisan calls should not delay the considerable work of Chairman Burr and Vice Chairman Warner. Too much is at stake.”

Vladimir Putin responds to James Comey firing: 'We had nothing to do with it'

In a brief letter to Mr Comey that was delivered to the FBI headquarters in Washington by hand, Mr Trump told the 56-year-old he had been fired as part of an effort to restore “public trust and confidence” in the FBI. Other officials, Mr Rosenstein among them, claimed one of the main reasons was Mr Comey’s handling of the investigation into Hillary Clinton’s use of a private email server, something for which Mr Trump had praised the FBI Director during the election campaign.

Mr Trump on Wednesday also defended the move to fire him, first on Twitter and later again when he appeared in the Oval Office with former Secretary of State Henry Kissinger. “He wasn’t doing a good job. Very simply. He was not doing a good job,” said a stern-looking Mr Trump.

At a press briefing at the White House, Deputy Press Secretary Sarah Huckabee Sanders said that the FBI Director had committed “atrocities”.

But there were many people, who did buy the explanation of Mr Trump of the flurry of surrogates who rushed to defend him in the television studios.

Many seized on the revelation that in the days before his firing, Mr Comey had asked the Justice Department for extra resources to help him pursue the investigation into Russia’s alleged interference in the election. The person he spoke to on that occasion was Mr Rosenstein.

Senate Intelligence Committee chairman Richard Burr, a Republican, and Democrat ranking member Mark Warner, said they had asked Mr Comey to appear before the committee next Tuesday.

Jeanne Zaino, Professor of Political Science at Iona College in New York, said the future of the investigation into Mr Trump would now rely to a great degree on the behaviour of Republicans in the Senate.

If sufficient pressure was exerted on Mr McConnell, he may be obliged to give in to agreeing to the appointment of a special prosecutor.

“Donald Trump did this to himself,” she told The Independent. “He went and threw gas on the fire. Had he not done this, the investigation would have stayed with the FBI. [The prospect of a special prosecutor] is 100 per cent more likely than at 5pm on Tuesday.”

In a series of early morning tweets, Mr Trump had said that both Republicans and Democrats “will be thanking me” for his action. He did not mention any effect the dismissal might have on the FBI and congressional investigations into contacts between his 2016 election campaign and Russia.

Outside the White House, a small group of protesters held placards and banners. They made it clear they did not agree with Mr Trump’s actions or his assessment of what he had done.

Carrying a sign that said “I smell impeachment and other foul smells”, Hannah Bradford, 54, said she thought the president had “no idea what he’s doing”. “He’s just flailing,” she added.