WASHINGTON - Acting White House Chief of Staff Mick Mulvaney told reporters Thursday that President Donald Trump blocked nearly $400 million in military aid to Ukraine in part to force the government in Kyiv to investigate his political rivals, a startling acknowledgment after the president’s repeated denials of a quid pro quo.

Mulvaney defended the maneuver as "absolutely appropriate."

"Did he also mention to me in the past the corruption related to the DNC server? Absolutely, no question about that. But that's it, that's why we held up the money," Mulvaney said, referring to a conspiracy theory that a hacked Democratic National Committee computer server was taken to Ukraine in 2016 to hide evidence that Kyiv, not Moscow, interfered in the last U.S. presidential election.

Mulvaney also said the funds had been withheld because European countries were being "really, really stingy when it comes to lethal aid" for Ukraine. But he characterized the decision to leverage congressionally approved aid as common practice, citing other instances in which the Trump administration has withheld aid to foreign countries and telling critics to "get over it."

"I have news for everybody: get over it. There's going to be political influence in foreign policy," Mulvaney said. "Elections do have consequences and they should, and your foreign policy is going to change . . . there's no problem with that."

Mulvaney’s news conference came as the U.S. ambassador to the European Union, Gordon Sondland, met behind closed doors with House impeachment investigators, telling them that Trump outsourced the job of handling U.S. policy on Ukraine to Trump’s personal attorney Rudy Giuliani, a decision that made Sondland uncomfortable but one he still carried out.

"I would not have recommended that Mr. Giuliani or any private citizen be involved in these foreign policy matters," Sondland said, according to his prepared remarks obtained by The Washington Post.

Mulvaney shot down those concerns, defending the president's right to put foreign policy in the hands of his personal lawyer.

“You may not like the fact that Giuliani was involved, that’s great, that’s fine,” Mulvaney said, referencing Sondland’s remarks. “It’s not illegal, it’s not impeachable. . . . The president gets to set foreign policy and he gets to choose who to do so, as long as it doesn’t violate any law.”

Sondland, a major Trump donor who has became a focus of the impeachment inquiry due to his outsized role in U.S.-Ukraine policy, criticized the president's temporary hold on aid and the recall of the former U.S. ambassador to Ukraine, Marie Yovanovitch. Sondland called her an "excellent diplomat" and said he "regretted" her departure, which followed a campaign by Giuliani to paint her as disloyal to the president.

Sondland is expected to face an onslaught of questions from Democrats, who have accused the president of abusing his power to pressure Ukraine to help his 2020 reelection campaign. Trump has denied any wrongdoing, and has said his decision to withhold military aid was out of frustration that European governments weren't doing more to assist the country.

In his remarks, Sondland said in principle he opposes any "quid pro quo" that would exchange U.S. support to a friendly nation for an investigation into Trump's political rival, former vice president Joe Biden. But he said he became aware only recently that Trump's efforts to investigate an obscure Ukrainian energy company named Burisma were due to its associations with Biden, whose son Hunter worked for the energy company. Joe Biden is a leading Democratic candidate for president.

"I did not understand, until much later, that Mr. Giuliani's agenda might have also included an effort to prompt the Ukrainians to investigate Vice President Biden or his son or to involve Ukrainians, directly or indirectly, in the President's 2020 reelection campaign," he said. "Although Mr. Giuliani did mention the name 'Burisma' in August 2019, I understood that Burisma was one of many examples of Ukrainian companies run by oligarchs and lacking the type of corporate governance structures found in Western companies."

Sondland's apparent failure to connect the dots between Burisma and the Bidens occurred as Giuliani made several televised appearances over the spring and summer criticizing Hunter Biden's involvement on the board, and numerous newspaper and magazine articles questioned whether his role at Burisma could prove to be a drag on his father's presidential campaign.

In his testimony, Sondland, a hotel magnate who came to the job with no diplomatic experience, depicts himself as a well-meaning but in some cases out of the loop emissary for the president who tried to do what he could to prop up the government of Ukraine as it fends off Russian-backed separatists.

"My goal has always been to advance U.S. interests in securing a strong relationship with Ukraine," he said in his remarks. "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."

Parts of his testimony appear to conflict with the testimony of other officials this week, including Fiona Hill, the National Security Council's former senior director for Russia and Europe. Hill told House investigators that she was concerned by Sondland's talk of investigations in a July meeting, which she eventually relayed to a lawyer for the National Security Council.

Sondland, in his opening remarks, said was never aware of objections from her or her boss, national security adviser John Bolton. "I have to view her testimony - if the media reports are accurate - as the product of hindsight and in the context of the widely known tensions between the NSC, on the one hand, and the State Department, on the other hand," he said.

Sondland claims that his pursuit of investigations in Ukraine were always in line with long-standing U.S. policy to push for transparency and anti-corruption efforts in the country.

-- John Hudson and Karoun Demirjian, The Washington Post