A campaign calling for the impeachment of Donald Trump has had more than 773,000 signatures.

The Impeach Trump Now movement is led by non-profit advocacy groups RootsAction and Free Speech for People, who claim that the US is witnessing a “massive corruption of the presidency, far worse than Watergate”.

The website, which went live on the same day as Trump was sworn in, says it will put a case forward to congress to investigate if there are significant grounds for Trump to be impeached.

In order to be impeached, congress would need to find Trump guilty of bribery, treason or “other high crimes and misdemeanours”.

Charges of impeachment have been levelled at three US presidents so far: Andrew Johnson in 1868, Bill Clinton in 1999 and Richard Nixon in 1974.

'Articles of impeachment' are decided upon by the House of Representatives. The members of the House Justice Committee decide by vote whether or not send the case to the Senate.

This is akin to a prosecutor deciding whether or not they have enough of a case before sending it to court.

The Senate then votes on whether or not convict a president. A two thirds majority is required to do so.

Impeach Trump Now have said Trump’s business activity violates the US constitution’s rule against receiving foreign emoluments, which states:

[N]o Person holding any Office of Profit or Trust under [the United States], shall, without the Consent of the Congress, accept of any present, Emolument, Office, or Title, of any kind whatever, from any King, Prince, or foreign State.

According to Impeach Trump Now, many of Trump Organization’s business dealings with foreign governments and businesses owned by foreign governments violate this.