Acting White House chief of staff Mick Mulvaney said Thursday that President Donald Trump — who is facing an impeachment inquiry because of controversial contacts with Ukraine — did not withhold congressionally appropriated military aid to Ukraine as part of a quid pro quo to get that country to investigate former Vice President Joe Biden.Instead, Mulvaney told reporters that the withholding of almost $400 million in aid this summer was due in part because Trump wanted Ukraine to investigate the possibility that elements in that country somehow had interfered in the 2016 U.S. presidential election to Trump’s detriment.”The money held up had absolutely nothing to do with Biden,” Mulvaney said.Instead, he said, the withholding of aid came in connection with “an ongoing investigation into the 2016 election,” and the possibility that a Democratic National Committee server that investigators have said was hacked by Russian agents ended up in Ukraine.While Mulvaney did not himself use the term “quid pro quo,” when he was told by a reporter during a White House news conference that the situation of withholding aid to get Ukraine to conduct a probe at Trump’s request was in fact a quid pro quo, Mulvaney said, “We do that all the time.”Referring to a conversation with Trump, Mulvaney said, “Did he also mention to me in passing the corruption related to the DNC server? Absolutely,””No question about that. But that’s it, and that’s why we held up the money.””You’re saying the president of the U.S. can’t ask someone to help with an ongoing public investigation?” Mulvaney said.Later Thursday, amid a wave of criticism, Mulvaney sharply walked back his comments.”Let me be clear, there was absolutely no quid pro quo between Ukrainian military aid and any investigation into the 2016 election,” he said in the statement.”The president never told me to withhold any money until the Ukrainians did anything related to the server. The only reasons we were holding the money was because of concern about lack of support from other nations and concerns over corruption.”During a July 25 phone call with Ukrainian President Volodymyr Zelensky — at a time when the White House was withholding military aid from Zelensky’s country — Trump asked Zelensky to “get to the bottom” of questions about the 2016 election.But Trump also asked him during the same call to speak with Attorney General Bill Barr “to look into” Biden allegedly stopping “the prosecution” of Biden’s son, Hunter Biden, while serving as vice president.A senior Justice Department official told NBC News, before Mulvaney walked back his comments, that “if the White House was withholding aid from Ukraine with regard to any investigation by the Justice Department, that’s news to us.”Trump’s personal attorney Jay Sekulow, in a brief statement before Mulvaney’s about-face, said, “The President’s legal counsel was not involved in acting chief of staff Mick Mulvaney’s press briefing.”The idea that Ukraine interfered in the 2016 election is a conspiracy theory often promoted by supporters of Trump. It relates in part to the suspicion that Ukrainians revealed actual or false financial information about Paul Manafort, a longtime Republican operative who had led Trump’s campaign for several months and who had worked for a pro-Russia political party in Ukraine.Federal investigators and intelligence agencies have said that Russian agents — not Ukrainian agents — interfered in the election to help Trump’s candidacy and hurt that of Democratic nominee Hillary Clinton.The House is conducting an impeachment inquiry into Trump because of a belief among congressional Democrats that the president used military aid and the potential of a meeting with Trump to pressure Zelensky, Ukraine’s new president, to launch an investigation of Biden.Rep. Adam Schiff, a California Democrat who heads the House Intelligence Committee and who is playing a leading role in the impeachment probe, when asked about Mulvaney’s admission of a quid pro quo, said, “With his acknowledgement now that military aid to a vital ally, a ally battling Russia as we speak, was withheld in part out of a desire by the president to have Ukraine investigate the DNC server or Democrats or 2016, things have just gone from very, very bad to much, much worse.The idea that vital military assistance would be withheld for such a patently political reason for the reason of serving the president’s reelection campaign is a phenomenal breach of the president’s duty to defend our national security and I hope that every member, Democrat and Republican, will speak out and condemn this illicit action by the president and his chief of staff.”Trump and his personal lawyer Rudy Giuliani have argued that Biden, while serving as vice president, pressured Ukraine to dismiss a prosecutor in that country in order to thwart a supposed investigation into a Ukrainian natural gas company on whose board Biden’s son, Hunter, served. Joe Biden is seeking the Democratic nomination for president in 2020.There is no evidence that Hunter Biden was or would have been eyed in such a probe.And Joe Biden’s pressure on Ukraine to terminate the prosecutor was in line with moves by other European countries that believed the prosecutor was not doing enough to target corruption in Ukraine.On Thursday, Gordon Sondland, U.S. ambassador to the European Union, was expected to tell House investigators that he had called Trump directly after hearing “many versions of speculation that had been circulating” about why military aid had been withheld from Ukraine.”I asked the president: ‘What do you want from Ukraine?'” Sondland said in a copy of his planned statement to the House. “The president responded: ‘Nothing. There is no quid pro quo.'””The president repeated: ‘no quid pro quo’ multiple times,” Sondland planned to testify. “This was a very short call. And I recall the president was in a bad mood.”At the same news conference Thursday, Mulvaney said that the United States had selected a Trump resort property in Florida, Trump National Doral Miami, for the G-7 summit next June.