NEW YORK - US President Donald Trump called himself the “greatest of all Presidents” as his Democratic opponents are holding meetings to prepare impeachment charges against him.

The House of Representatives’ Judiciary Committee is expected to draft at least three articles of impeachment -- essentially charges of wrongdoing -- against Trump which the whole House  is expected to vote on before Christmas.

Those articles could include abuse of power through bribery, obstruction of Congress and obstruction of justice.

Attacking House Speaker Nancy Pelosi, a Democrat, for not passing his signature trade bill, Trump, in a tweet, went after democrats for trying to impeach him — stating they were making a big mistake. On Saturday, the Committee’s democratic lawmakers released a 55-page report detailing offences that could warrant impeachment against the Republican President.

The report covers the “Constitutional grounds for Presidential impeachment,” including bribery, abuse of power, betrayal of US national interest and corruption.

It refers to the writings of former President George Washington and Thomas Jefferson and follows a hearing last week in which three of four Constitutional law experts giving evidence said they believed  Trump’s actions had met the bar for impeachment.

If the House does vote to impeach the President as expected, the Senate will hold a trial next year. In theory it could remove him from office, or censure him, if two-thirds of Senators vote to do so. But since the Upper House is controlled by his Republican allies it looks unlikely to do so.

The President is accused of abusing his power by pressuring his  Ukrainian counterpart Volodymyr Zelensky to smear his democratic opponents in return for releasing foreign aid and arranging a symbolically important White House meeting.

Trump kept up his angry denials and counter-accusations on Twitter on Saturday, at one point claiming that he was the “greatest of all Presidents”.