WASHINGTON - The White House admitted Thursday that U.S. President Donald Trump froze $400 million in badly needed military aid to Ukraine to pressure it into investigating Democrats and the 2016 presidential election.

The stunning revelation by acting chief of staff Mick Mulvaney came after Trump spent weeks denying there was any quid pro quo with Ukraine.

Mulvaney told reporters at the White House the money for Ukraine was being held up because of Trump's concerns over corruption in Ukraine and suspicions it was involved in the Russian hacking of the Democratic National Committee e-mails in 2016.

The allegation was based on conspiracy theories and has been debunked.

Mulvaney defiantly said there will always be political influence over foreign policy and told people to "get over it."

Mulvaney issued a statement late Thursday attempting to clear up his comments that suggested there was a quid pro quo with Ukraine.

"The only reasons we were holding up the money was because of concern about a lack of support from other nations and concerns over corruption."

Mulvaney accused the media of "misconstruing" what he said to benefit a "biased and political witch hunt" against Trump.

But Democratic Representative Adam Schiff, who is leading the impeachment inquiry into Trump, said "I think Mr. Mulvaney's acknowledgement means that things have gone from very very bad to much much worse."

Trump's legal team distanced itself from Mulvaney. Presidential lawyer Jay Sekulow, said he and others were not involved in Mulvaney's appearance before the press.

The U.S. Justice Department said if the White House froze aid to Ukraine while seeking an investigation, "It is news to us."

Mulvaney's stated reasons for holding up aid to Ukraine are separate from the focus of the impeachment probe - whether Trump pressured Ukraine to investigate Democratic presidential candidate Joe Biden and his son, Hunter Biden.

House committees Thursday heard testimony from the U.S. Ambassador to the European Union and major Trump campaign donor Gordon Sondland.

Sondland told the lawmakers that Trump ordered him and other diplomats to work with the president's personal lawyer, Rudy Giuliani, to pressure Ukraine into investigations that could help Trump politically.

Those investigations would include the 2016 election and the Ukrainian gas company where Hunter Biden worked.

Sondland told the investigators he was disappointed that Trump directed diplomats to work with Giuliani on Ukraine matters.

"Our view was that the men and women of the State Department, not the president's personal lawyer, should take responsibility for all aspects of U.S. foreign policy towards Ukraine," Sondland said.

He said the diplomats who worked with Giuliani did not know "until much later" that Giuliani would push for a probe of Biden "or to involve Ukrainians, directly or indirectly, in the president's 2020 re-election campaign."

"Let me state clearly: Inviting a foreign government to undertake investigations for the purpose of influencing an upcoming U.S. election would be wrong," Sondland said in his statement. "Withholding foreign aid in order to pressure a foreign government to take such steps would be wrong. I did not and would not ever participate in such undertakings." Trump eventually released the military aid to Kyiv.

The Trump-Ukraine scandal was set off when an intelligence whistleblower expressed concern to the inspector general about Trump's July 25 telephone call with Ukrainian President Volodymyr Zelenskiy.

A White House-released transcript of the call shows Trump apparently urging Zelenskiy to open a corruption investigation into the Bidens, including Hunter Biden's job the Ukrainian gas company.

Trump has alleged that when Joe Biden was U.S. vice president, he threatened to withhold loan guarantees to Ukraine unless an earlier corruption probe into the gas company was stopped.

No evidence of wrongdoing by Joe or Hunter Biden has surfaced. But reaching out to a foreign government to dig up dirt on a rival is considered to be interference in a presidential election and an impeachable offense.

Trump has describes his call with Zelenskiy as "perfect" and accuses the Democratic-led House of a witch hunt.