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Donald Trump’s White House has become engulfed in controversy after the US President fired the FBI director leading an investigation into his administration’s links to Russia. Democratic Congressman Al Green is the latest Democrate to call for impeachment saying Mr Trump “acknowledged he considered the investigation” when he fired Mr Comey. The Democrat said: “I have said on previous occasions, and do now say again, the President should be impeached.” The call for impeachment came amid controversy over an explosive memo written by Mr Comey that claimed the US President asked him to shut down the Flynn investigation.

The memo reports that Mr Trump asked Mr Comey to 'let go' of an investigation into his former national security adviser, Michael Flynn and his links with Russia. After the sacking of Mr Comey, Democratic Senator Richard Blumenthal told CNN: "It may well produce impeachment proceedings, although we're very far from that possibility." Mr Trump has rejected accusations of a cover-up and has said that he fired the ‘showboat’ over his mishandling of the Hillary Clinton email scandal. The chances of Mr Trump being impeached are now just 2/1, according to the latest odds from Betfair.

Reuters Donald Trump and Vice President Mike Pence during the National Peace Officers Memorial Service

How does impeachment work? In order to face impeachment, the President needs to be accused of “treason, bribery, or other high crimes and misdemeanours”. If the House of Representatives votes to impeach the President, then he gets impeached but is not expelled from office at this stage of the process. There will then be an impeachment trial in the Senate where a two-thirds majority vote is needed to convict the president and remove him from office. Both the House and the Senate are controlled by Republicans who are politically aligned with Mr Trump and unlikely to turn against him as yet. The House has only impeached two presidents before - Andrew Johnson and Bill Clinton. Both were later acquitted in the Senate and stayed in office. Richard Nixon resigned in order to avoid impeachment and expulsion from office in the wake of the Watergate scandal that rocked the White House.

Donald Trump's historic inauguration in pictures Mon, January 23, 2017 The inauguration of Donald Trump as the 45th President of the United States marked commencement of the four-year term as President and Mike Pence as Vice President. Play slideshow AP 1 of 40 President Donald Trump waves as he walks with first lady Melania Trump and son Barron during the inauguration parade.