A US political veteran says Donald Trump could face impeachment, if allegations he tried to interfere with an FBI investigation are true.

The US Senate Intelligence Committee is requesting memos detailing meetings between former FBI director James Comey and the President.

It is alleged Mr Trump asked Mr Comey to drop an investigation into former national security adviser Michael Flynn over his ties to Russia.

Former National Republican National Committee Doug Heye told Rachel Smalley claims against the President are mounting.

"We certainly need to see what is in the Comey memos and so forth. If there was allegations that can be proven true, that could be an impeachable offence."

Heye said Trump is also copping heavy criticism for allegedly sharing classified intelligence with the Russian Foreign Minister.

"I think this was a big mistake by the President, certainly our allies will look at and determine how they deal with our government in the future somewhat differently."

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