What is impeachment? President may face charges but Republican majority in the House could protect him

Impeachment is the process by which Congress can put certain officials, including the president, on trial. The constitution lays out a broad scope of offences that can lead to impeachment, including “treason, bribery, or other high crimes and misdemeanours”.

A move to impeach does not necessarily mean the president will be forced from office. A vote must proceed like a Bill passing through legislature. First, a majority in the House of Representatives – 218 out of 435 members – must approve articles of impeachment previously approved in committee.

The current make-up of the House favours Donald Trump. Republicans hold 238 seats, while Democrats hold 193 (four seats are vacant). That means 25 Republicans would need to be persuaded to vote to impeach Mr Trump, which could protect him.

The vote then goes to the Senate, where a two thirds majority vote is needed to convict the president and oust him from office. There have been two presidents who have been impeached in the past and neither was removed from office.

Andrew Johnson went through the process in 1868 after he tried to replace the US secretary of war without congressional permission. His impeachment passed to the Senate, where he escaped being removed from office by a one-vote margin.

The other president was Bill Clinton, over the Monica Lewinsky scandal. He was impeached for perjury and obstruction of justice in 1998, but he was acquitted in the Senate.

Richard Nixon would almost certainly have faced impeachment in 1974 over the Watergate scandal, but the disgraced president resigned first.

There have been calls for action against Mr Trump over claims that he shared classified information with Russia. But if true, it is unlikely he has broken any law.

The latest controversy could be trickier. Allegations of obstruction of justice were levelled against the president as soon as he fired FBI director James Comey,

pictured, who was leading an investigation into the Trump campaign’s links to Russia.

But the case against Mr Trump would have to be damning and watertight for Republicans to act against him. Chris Graham