Trump wasn't simply firing the FBI Director. He was firing the man overseeing the investigation into Trump's team and ties to Russia leading up to last November's election.
The firing was recommended by Attorney-General Jeff Sessions, who had to previously recuse himself from the Russia probe.
The Comey sacking occurred as CNN reported that grand jury subpoenas were issued in the FBI's Russia probe of associates of former National Security Adviser Michael Flynn and a day after former acting AG Sally Yates' testimony about Flynn.
Republican Senator Richard Burr, who heads the Intelligence Committee, said he was "troubled by the timing and reasoning of Director Comey's termination".
It goes without saying, this is a major political gamble by Trump. It kicks up so many questions that will swirl and settle over the Administration.
Demands for an independent special counsel to investigate Russia's role in last year's election are intense.
Comey knows a lot. So, for that matter, does Flynn. Senator Ron Wyden tweeted: "Comey should be immediately called to testify in an open hearing about the status of Russia/Trump investigation at the time he was fired".
And yet, the Trump Administration will get to appoint a new FBI Director. Republican lawmakers mostly lined up to back Trump and the party controls Congress.
NBC reporter Ken Dilanian tweeted: "Former senior FBI official tells me: 'I believe the intent here is to replace him with someone who will close' the Russia probe."
Politico reported that Trump has become enraged about the Russia probe, "screaming" at television clips about it and asking aides why it won't go away.
The strangest note heard yesterday was the Trump Administration using Comey's treatment of Hillary Clinton's emails as the reason to sack him. If that really was the reason, there was no need to keep Comey on in January when Trump took over.
Former Clinton campaign manager Robby Mook reacted: "Twilight zone. I was as disappointed and frustrated as anyone at how the email investigation was handled. But this terrifies me."
English coy on Comey firing
Prime Minister Bill English says the abrupt sacking of FBI director James Comey is "a matter for President Trump".
English met Comey only weeks ago at a gathering of intelligence and security agencies related to the Five Eyes spying network in Queenstown.
Asked for his impressions of the former FBI director, English said "he was just the usual, professional, civilised senior American public servant".
SIS and GCSB Minister Chris Finlayson said he had met with Comey on a number of occasions, and said "he struck me as a very nice man".
He would not comment on Comey's dismissal, saying he "did not get into those things because it's a sovereign country and it would be inappropriate".
President Donald Trump's decision to fire Comey ignited a political firestorm in Washington. A White House statement announced that Trump told Comey "that he has been terminated and removed from office".
"A search for a new permanent FBI Director will begin immediately."
Trump acted on the advice of Attorney General Jeff Sessions, who stated the government needed to "reaffirm its commitment" to "the integrity and fairness of federal investigations and prosecutions".
- Additional reporting news.com.au
