A campaign calling for the impeachment of Donald Trump has passed over 500,000 signatures.

The Impeach Trump Now movement, is lead by "a national non-partisan non-profit organisation," Free Speech for People, who claim that the nation is witnessing 'a massive corruption of the presidency, far worse than Watergate'.

Impeachment is the process of bringing charges against a high official of Government by a legislative body. It typically comes in the form of a resolution, calling for a committee investigation of charges against the officer in question.

In the past, three Presidents have had proceedings brought against them: Andrew Johnson in 1868, Bill Clinton in 1999 and Richard Nixon in 1974. Johnson and Clinton were impeached by the House of Representatives but were acquitted in the Senate. While Nixon resigned before he could be impeached.

Impeach Trump Now explain:

President Trump’s personal and business holdings in the United States and abroad present unprecedented conflicts of interest. Indeed, President Trump has admitted he has conflicts of interest in some cases.

The group alleges that Mr Trump's business dealings "violate the U.S. Constitution’s Foreign Emoluments," which states that “[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 the Trump Organization’s extensive business dealings with foreign governments, businesses owned by foreign governments, and other foreign leaders violate this ban.

They also touch on the the Constitution’s Domestic Emoluments Clause (also known as the Presidential Compensation Clause), which states that;

The President shall, at stated Times, receive for his Services, a Compensation, which shall neither be encreased nor diminished during the Period for which he shall have been elected, and he shall not receive within that Period any other Emolument from the United States, or any of them.

In addition, the group request the committee to investigate whether Mr Trump is violating the Stop Trading on Congressional Knowledge Act of 2012.

This piece of legislation prohibits a President from using nonpublic information for private profit, and "from intentionally influencing an employment decision or practise of a private entity solely on the basis of partisan political affiliation."

Ron Fein, Legal Director of Free Speech For People, said in a statement: