Washington, May 10 (IANS) US President Donald Trumps decision to fire FBI Director James B. Comey revived calls by Democratic lawmakers for an independent investigation of Russian meddling in US elections, with many calling for the appointment of a special prosecutor.

"We are in a full-fledged constitutional crisis," Senator Brian Schatz tweeted after the White House announced Comey's dismissal on Tuesday.

"This is Nixonian," added Senator Robert Casey.

Trump suddenly dismissed Comey, who had earned the wrath of the Democratic Party for his interference in last year's elections, but was in the middle of an investigation into whether Trump's campaign had links to Russia.

Aides described Democratic senators as "shaken and alarmed" by the surprise announcement and the news of Comey's ouster sparked several conversations among Democratic senators about how they should respond, the Washington Post reported.

In a written statement Tuesday evening, Senate Majority Leader Mitch McConnell said nothing about Comey -- only that Trump's new nominee for FBI director would receive "a full, fair, and timely confirmation process".

Republican Senator John McCain of Arizona called for the creation of a special congressional committee on Russia, while Republican Representative Justin Amash of Michigan said he and his staff were "reviewing legislation to establish an independent commission on Russia".

"James Comey is a man of honour and integrity, and he has led the FBI well in extraordinary circumstances," McCain said.

Comey, a Republican who had served in the George W. Bush administration as second in command in the Justice Department, was the surprise choice of President Barack Obama for the FBI post.

Democratic aides said they were "heartened" to see several senior Republicans cast doubt on Trump's decision to fire Comey.

They especially cited Senate Intelligence Committee Chairman Richard Burr and Senate Foreign Relations Committee Chairman Bob Corker and Senator Jeff Flake, who is up for reelection next year in a contest that Democrats believe could become competitive if anti-Trump sentiments sweep the nation.

Burr, who is leading the intelligence panel's probe of Russian meddling, said in a statement that he is "troubled by the timing and reasoning" for Comey's firing.