By Steve Holland

WASHINGTON (Reuters) – U.S. President Donald Trump on Monday rejected the Democratic-led House of Representatives’ impeachment charges, describing the allegations that he had abused his power and obstructed Congress as affronts to the U.S. Constitution that must be rejected.

“The Senate should speedily reject these deficient articles of impeachment and acquit the president,” an executive summary of the Republican president’s pre-trial brief said in Trump’s first comprehensive defense before the start of his Senate trial.

Trump, only the fourth of 45 American presidents to face the possibility of being ousted by impeachment, is charged with abusing the powers of his office by asking Ukraine to investigate a Democratic political rival, Joe Biden, and obstructing a congressional inquiry into his conduct.

The executive summary asserted that the “House Democrats theory of ‘abuse of power’ is not an impeachable offense.” It rejected the obstruction of Congress charge as frivolous and dangerous, saying the president exercised his legal rights by resisting congressional demands for information.

It accused the House Democrats of conducting a rigged process and said they succeeded in proving that Trump had done nothing wrong.

While the Republican-controlled Senate is highly unlikely to remove Trump from office, it is important for the Republican president to diminish the Democratic accusations as a partisan witch-hunt. He needs to limit the political damage to his re-election bid as he seeks a second term in November.

Trump’s legal team says he was well within his constitutional authority to press Ukraine President Volodymyr Zelenskiy last year to investigate Biden and his son Hunter as part of what Trump says was an anti-corruption drive. The Bidens deny any wrongdoing and Trump’s allegations have been widely debunked.

Democrats say Trump abused his power by withholding U.S. military assistance to Ukraine as part of a pressure campaign and obstructed Congress by refusing to hand over documents and barring administration officials from testifying, even when subpoenaed by House investigators.

Trump’s team says he is protected by the U.S. Constitution’s separation of powers provisions.

In a 111-page document filed before the Senate trial begins in earnest on Tuesday, Democratic lawmakers laid out their arguments against Trump, saying the president must be removed from office to protect national security and preserve the country’s system of government.

Seeking to show he is still conducting presidential business despite the trial, Trump is scheduled to depart late on Monday for Davos, Switzerland, to join global leaders at the World Economic Forum. Some advisers had argued against him making the trip.

(Reporting by Steve Holland; Writing by Arshad Mohammed; Editing by Ross Colvin, Daniel Wallis and Bernadette Baum)