WASHINGTON — Mick Mulvaney, the acting White House chief of staff, said Thursday that the Trump administration withheld nearly $400 million in military aid to pressure Ukraine to investigate what the president has long insisted was Kiev’s assistance to Democrats during the 2016 election.
The declaration by Mr. Mulvaney — which he then took back later in the day — undercut Mr. Trump’s repeated denials of a quid pro quo that linked American military aid for Ukraine to investigations that could help him politically.
Mr. Trump had pushed Ukraine to open an investigation into an unsubstantiated theory that Ukraine, not Russia, was responsible for hacking Democratic party emails in 2016 — a theory that would show that Mr. Trump was elected president without Russian help.
A former White House homeland security adviser had told Mr. Trump that the theory had been “completely debunked.” But Mr. Trump demanded Ukraine take a look, Mr. Mulvaney said.
“The look back to what happened in 2016 certainly was part of the thing that he was worried about in corruption with that nation,” Mr. Mulvaney told reporters, referring to Mr. Trump. “And that is absolutely appropriate.”
Mr. Mulvaney’s acknowledgment of a tie between military aid and a political investigation came as House Democrats were summoning a stream of witnesses to the Capitol to investigate whether Mr. Trump had pressured Ukraine for his personal political benefit in 2020. Mr. Mulvaney effectively threw the Republican defense of the president into disarray.
Democrats called Mr. Mulvaney’s comments a potential turning point in their impeachment inquiry. “We have a confession,” said Representative Eric Swalwell, Democrat of California.
By day’s end, Mr. Mulvaney had issued a statement flatly denying what he had earlier said at a briefing for reporters in the White House.
“Once again, the media has decided to misconstrue my comments to advance a biased and political witch hunt against President Trump,” he wrote. “Let me be clear, there was absolutely no quid pro quo between Ukrainian military aid and any investigation into the 2016 election. The president never told me to withhold any money until the Ukrainians did anything related to the server.”
But in his lunchtime remarks to reporters, Mr. Mulvaney pointed to “three issues” that explained why officials withheld the aid: corruption in Ukraine, frustration that European governments were not providing more money to Ukraine and the president’s demand that Kiev officials investigate the issue of the Democratic National Committee server.
“Did he also mention to me in passing the corruption related to the D.N.C. server?’’ Mr. Mulvaney said, referring to Mr. Trump. “Absolutely. No question about that.” He added: “That’s why we held up the money.”
Democrats ridiculed the reversal.
“Mick Mulvaney was either lying then, or he’s lying now,” said Representative Ted Lieu, a California Democrat involved in the inquiry. “I think he’s lying now.”
At the White House, staff members recognized that Mr. Mulvaney had created an entirely new controversy with his remarks. Jay Sekulow, one of Mr. Trump’s personal lawyers, said Thursday, “The president’s legal counsel was not involved in acting chief of staff Mick Mulvaney’s press briefing.”
Mr. Mulvaney’s performance headlined another extraordinary day in Mr. Trump’s tenure. Mr. Mulvaney made his remarks after he stepped before the cameras to announce that leaders of the Group of 7 nations would meet in June at Mr. Trump’s golf resort in South Florida, even as he acknowledged the choice could be seen as self-enrichment. In Texas, Mr. Trump hailed a Middle East cease-fire that would cement Turkey’s goal of pushing Kurds from Northern Syria as “a great day for civilization.”
And on Capitol Hill, Gordon D. Sondland, the president’s ambassador to the European Union and a wealthy donor to Mr. Trump’s campaign, was implicating the president in the Ukraine scandal by telling lawmakers that Mr. Trump had delegated Ukraine policy to his personal lawyer Rudolph W. Giuliani.
Mr. Sondland testified behind closed doors for more than six hours, the latest in a series of current and former diplomats and White House aides who have provided detailed accounts of actions by Mr. Giuliani and others related to Ukraine.
Democratic lawmakers are certain to seize on Mr. Mulvaney’s comments as crucial support of the testimony coming from other witnesses, who have accused the administration of improperly pressuring Ukraine and of sidelining veteran diplomats in favor of Mr. Trump’s political loyalists.
But Mr. Mulvaney was defiant and unapologetic.
“I have news for everybody: Get over it. There’s going to be political influence in foreign policy,” he said, adding, “Elections have consequences.”
In wide-ranging remarks, Mr. Mulvaney told reporters at the White House that the $391 million in military aid was initially withheld from Ukraine because the president was displeased that European countries were not as generous with their assistance. He also wanted more attention paid to Ukraine’s persistent political corruption.
Mr. Mulvaney denied that the aid for Ukraine was also contingent on its government’s opening an investigation into either former Vice President Joseph R. Biden Jr., a leading Democratic candidate for president, or his younger son, Hunter Biden. Asked whether he did anything to pressure President Volodymyr Zelensky of Ukraine to investigate the Bidens, Mr. Mulvaney said no.
But the president did pressure Ukraine to re-examine discredited theories that Ukraine, not Russia, had worked to sway the 2016 campaign. Mr. Mulvaney’s mention of a “D.N.C. server” was a reference to an unfounded conspiracy theory promoted by Mr. Trump that Ukraine was somehow involved in Russia’s 2016 theft of emails from the Democratic National Committee and the Democratic Congressional Campaign Committee.
Mr. Mulvaney tied the server to the Justice Department’s review of the origins of the Russia investigation, led by the United States attorney in Connecticut, John H. Durham, and closely overseen by Attorney General William P. Barr.
“That’s an ongoing investigation,” Mr. Mulvaney said. “So you’re saying the president of the United States, the chief law enforcement person, cannot ask somebody to cooperate with an ongoing public investigation into wrongdoing? That’s just bizarre to me that you would think that you can’t do that.”
But while the Justice Department said last month that Mr. Durham was examining any role that Ukraine might have played in the early stages of the Russia investigation, a department official declined on Thursday to comment on whether he was examining the server conspiracy theory.
Russian military officers hacked Democratic servers to steal thousands of emails in 2016, the intelligence community and the special counsel found, and no one has uncovered evidence of Ukrainian involvement.
Justice Department officials were confused and angry when they heard that Mr. Mulvaney said the White House had frozen aid to Ukraine in exchange for help with the Durham investigation, according to a person familiar with their discussions.
“If the White House was withholding aid in regards to the cooperation of any investigation at the Department of Justice, that is news to us,” a senior Justice Department official said. Mr. Durham was seen leaving the Justice Department around midday Thursday.
Mr. Mulvaney said the president had done nothing improper and had stayed within normal diplomatic channels. He blasted the current and former administration officials who have testified in the impeachment inquiry, describing them as personally opposed to the changes in foreign policy that Mr. Trump had put in place.
“What you’re seeing now, I believe, is a group of mostly career bureaucrats who are saying, ‘You know what, I don’t like President Trump’s politics, so I’m going to participate in this witch hunt that they are undertaking on the hill.’”
Mr. Mulvaney said holding up Ukraine’s aid was a normal part of foreign policy, and he compared it to the foreign aid to Central America that the administration froze until Guatemala, El Salvador and Honduras agreed to adopt the immigration policies pressed by Mr. Trump.
Asked whether he had admitted to a quid pro quo, Mr. Mulvaney said, “We do that all the time with foreign policy.”
His answer ignored the distinction — raised by many of the president’s critics — between holding up foreign aid to further American interests and holding up foreign aid to further Mr. Trump’s personal interests.
Senior White House aides like Mr. Mulvaney are often largely immune from congressional subpoenas to discuss their private conversations with the president, but talking about them publicly in such an extended way could undermine that legal protection.
Democrats had already been interested in Mr. Mulvaney’s role in the Ukraine matter after several impeachment witnesses described him as a central player in the effort to hold up the aid in the days before Mr. Trump pressed Ukraine’s president to investigate Mr. Biden.
They also have said they want to know whether Mr. Mulvaney helped prevent a White House meeting between Mr. Trump and Mr. Zelensky until the Ukrainian government agreed to investigate the president’s rivals, including the D.N.C. and the Bidens.
Fiona Hill, the president’s former senior director for European and Russian affairs at the National Security Council, testified that Mr. Mulvaney was part of a trio of Trump loyalists who conducted a rogue foreign policy operation in Ukraine.
Ms. Hill told lawmakers that John R. Bolton, then the national security adviser, instructed her in early July to advise the National Security Council’s chief lawyer about the effort by Mr. Mulvaney, Mr. Sondland and Mr. Giuliani.
“I am not part of whatever drug deal Sondland and Mulvaney are cooking up,” Mr. Bolton told Ms. Hill to tell White House lawyers, according to two people at Ms. Hill’s deposition, which took place on Monday.
In his remarks on Thursday, Mr. Mulvaney said there was nothing wrong with Mr. Trump’s relying on Mr. Giuliani or others outside of the diplomatic corps to conduct foreign policy.
“That’s the president’s call,” he said. “You may not like the fact that Giuliani was involved. That’s great, that’s fine. It’s not illegal, it’s not impeachable.” He added, “The president gets to set foreign policy, and he gets to choose who to do so.”
Democrats are also eager to know about a May 23 meeting during which career diplomats with responsibility for Ukraine were sidelined in favor of Mr. Sondland, Kurt D. Volker, the special envoy for Ukraine; and Rick Perry, the energy secretary, one witness testified.
George P. Kent, the deputy assistant secretary in the Bureau of European and Eurasian Affairs, testified Tuesday that Mr. Mulvaney called the White House meeting, according to Representative Gerald E. Connolly, Democrat of Virginia, who was in the room for Mr. Kent’s testimony.
Katie Benner and Nicholas Fandos contributed reporting from Washington, and Maggie Haberman from New York.