The decision to fire James Comey amid the FBI's investigation into the President's ties to Russia outraged Democrats who warned of a Nixon-like constitutional crisis.

Donald Trump wrote to the bureau's director Comey on Tuesday afternoon saying: 'You are hereby terminated and removed from office immediately.'

Among Democrats, the reaction to Trump's dismissal of Comey was one of rage mixed with apprehension about the future of American democracy.

Maryland Senator Chris Van Hollen warned that the US was at 'a dark and dangerous moment in history.'

Van Hollen accused the president of igniting 'a crisis of confidence' in the Justice Department.

President Donald Trump's (left) decision to fire FBI Director James Comey (right) on Tuesday in the midst of the bureau's investigation into his campaign's possible ties to Russia outraged Democrats and liberal-leaning pundits who warned of a constitutional crisis

'Firing Comey has the foul stench of an attempt to stop an ongoing investigation into collusion between Trump campaign and the Russians,' he said.

Hawaii Senator Brian Schatz, a Democrat, tweeted: 'We are in a full-fledged constitutional crisis.'

Two Democratic senators, Bob Casey of Pennsylvania and Patrick Leahy of Vermont, described the decision by Trump to sack Comey as 'Nixonian.'

Another Democratic senator, Ed Markey of Massachusetts, said the decision had parallels to Nixon's firing of Watergate special prosecutor Archibald Cox in 1973.

Markey said that Trump's move 'is disturbingly reminiscent of the Saturday Night Massacre during the Watergate scandal and the national turmoil that it caused.'

PRESIDENT RICHARD NIXON'S 'SATURDAY NIGHT MASSACRE' Following the President's firing of FBI Director James Comey, who was the head of the investigation into collusion between Trump's administration and Russia, some were quick to ask whether or not this would be his 'Saturday Night Massacre'. In 1973, President Richard Nixon also fired the official responsible for investigating potential wrongdoing in his administration. On October 20, 1973, President Nixon fired independent special prosecutor Archibald Cox, who was head of the investigation into the Watergate Scandal. His firing lead to the resignations of Attorney General Elliot Richardson and Deputy Attorney General William Ruckelshaus. That Saturday night, news broadcast networks turned their airtime over to the 'firestorm' and 'constitutional crisis.' The pushback against these firings was so significant that Nixon was forced to name a new special prosecutor, Texas lawyer Leon Jaworski. The story then played out over the next 10 months, ending when a unanimous Supreme Court forced Nixon to hand over the tapes. Their contents proved the cover-up that led to Nixon's eventual resignation. Advertisement

Hawaii Senator Brian Schatz (left), a Democrat, tweeted: 'We are in a full-fledged constitutional crisis.' Maryland Senator Chris Van Hollen (right) warned that the US was at 'a dark and dangerous moment in history'

Senate Minority Leader Chuck Schumer (above) claimed the firing was a cover-up attempt over Trump's alleged links to Russia

'EVERYONE who cares about independence & rule of law in America should be "troubled by the timing and reasoning" of Comey firing. Period,' former US attorney Preet Bharara tweeted Tuesday in response to a Republican lawmaker, Richard Burr

'We are careening ever closer to a Constitutional crisis,' Markey said.

COMEY: NEW VICTIM OF CLINTON'S TOXIC EMAIL SCANDAL March 2015: It becomes publicly known that Hillary Clinton, during her tenure as United States Secretary of State, had used her family's private email server for official communications and FBI opened investigation. May 2016: The State Department's Office of the Inspector General released an 83-page report about the State Department's email practices, including Clinton's. July 2016: FBI director James Comey announces the bureau's investigation had concluded that Clinton was 'extremely careless' in handling her email system but recommended that no charges be filed against her. Two days later the State Department reopens its probe into the email controversy. September 2016: DailyMail.com reveals Huma Abedin's husband Anthony Weiner has sexted a 15-year-old girl. The FBI investigates Weiner, already known as a sexting-addicted pervert, for sexual contact with a minor October 2016: Eleven days before the election, Comey notifies Congress the FBI is reopening the case due to emails found on a laptop used by Weiner including some from Abedin's Clintonemail.com address November 2016: Comey notifies Congress the conclusion that Clinton is in the clear is unchanged - but day slater she loses the election. Democrats blame Comey. April 2017: Clinton surfaces to explicitly blame Comey, Russia and misogyny for her loss. May 2017: Comey 'misspeaks' in Senate testimony, saying Abedin sent hundreds or thousands of emails to her husband. In fact she only sent the pervert a handful. 9 May: Comey is dramatically fired with immediate effect by the president. Advertisement

Nixon's dismissal of Cox, who was investigating him for his role in the Watergate coverup, is widely viewed as leading to the president's eventual resignation.

Senate Minority Leader Chuck Schumer claimed the firing was a cover-up attempt over Trump's alleged links to Russia.

Schumer told reporters that the decision to dismiss Comey was 'a big mistake'.

'This is part of a troubling pattern from the Trump administration,' the New York Democrat said.

'They fired Sally Yates. They fired Preet Bharara. And now they fired director Comey, the very man leading the investigation. This does not seem to be a coincidence,' he said.

Bharara was dismissed by Trump from his post as US Attorney for the Southern District in New York in March - even though Trump had previously asked Bharara, a holdover from the Obama administration, to stay on weeks earlier.

'EVERYONE who cares about independence & rule of law in America should be "troubled by the timing and reasoning" of Comey firing. Period,' Bharara tweeted Tuesday in response to a Republican lawmaker, Richard Burr.

Schumer said that appointing a special prosecutor to investigate alleged ties between Trump and Russia was the 'only way to restore the American people's faith.'

Keith Ellison, a Congressman from Minnesota, said: 'We are witnessing a Constitutional crisis unfold before our very eyes.'

Pundits were also beside themselves in reacting to the news.

Jeffrey Toobin, a commentator for CNN, condemned Trump's 'grotesque abuse of power.'

'This is the kind of thing that goes on in non-democracies,' Toobin said.

'That when there is an investigation that reaches near the president of the United States, or the leader of a non-democracy, they fire the people who are in charge of the investigation.'

Jeffrey Toobin, a commentator for CNN, condemned Trump's 'grotesque abuse of power'

Toobin and others have likened Trump's dismissal of Comey to former President Richard Nixon's (left) firing of Archibald Cox (right) in 1973. Cox was a special prosecutor who was looking into allegations of wrongdoing by Nixon and his aides in the Watergate affair

'This is not normal,' Toobin said.

'This is not politics as usual. This is something that is completely outside how the American law is supposed to work.'

'This is a political act when the president is under investigation,' Toobin said.

'When his White House counsel was described yesterday as being told that his National Security Adviser was subject to blackmail by the Russians and they fired the attorney general a few days later,' he said, referring to Sally Yates.

'Now they've fired the FBI director. I mean, what kind of country is this?'