WASHINGTON (Reuters) - U.S. House of Representatives committees conducting an impeachment inquiry of President Donald Trump said on Tuesday they had asked Mick Mulvaney, the acting White House Chief of Staff, to appear for a deposition on Nov. 8, a request he intends to ignore.

FILE PHOTO: Acting White House Chief of Staff Mick Mulvaney listens during a cabinet meeting held by U.S. President Donald Trump at the White House in Washington, U.S., October 21, 2019. REUTERS/Leah Millis/File Photo

The request for testimony from Mulvaney, a former Republican House member who is now the president’s top aide, ratcheted up the escalating conflict between the Democratic-controlled House investigation and the Republican White House over the probe.

“Based on evidence gathered in the impeachment inquiry and public reporting, we believe that you possess substantial first-hand knowledge and information relevant to the House’s impeachment inquiry,” leaders of the House Foreign Affairs, Intelligence and Oversight committees said in a letter to Mulvaney.

The White House said Mulvaney did not intend to comply with the request.

“Past Democrat and Republican Administrations would not be inclined to permit Senior Advisers to the President to participate in such a ridiculous, partisan, illegitimate proceeding – and neither is this one,” spokesman Hogan Gidley said in an emailed statement.

Mulvaney has emerged as a central figure in the impeachment inquiry, including his statement at an Oct. 17 news conference that the White House had withheld security assistance for Ukraine.

“I have news for everybody: Get over it. There is going to be political influence in foreign policy,” Mulvaney said at the time, although he later contradicted himself.

Before becoming acting chief of staff, Mulvaney ran the White House Office of Management and Budget, which made the decision to block nearly $400 million in security assistance for Ukraine last summer.

Mulvaney had already disregarded a congressional subpoena to turn over documents in the inquiry, and his close aides who have been asked to testify have refused to show up.

House investigators are trying to determine whether Trump withheld the assistance to pressure Ukraine’s government to investigate the son of former Vice President Joe Biden, one of Trump’s main rivals as he seeks re-election next year.

Trump denies wrongdoing.