(CNN) President Donald Trump is not pleased with acting chief of staff Mick Mulvaney's press briefing and his acknowledgment on Thursday of a quid pro quo, according to a source close to the President.

"He was not happy," the source said.

Mulvaney shocked reporters when he admitted the Trump administration had held up military funding to Ukraine to press the country to investigate the handling of a Democratic National Committee server hacked in the 2016 election. When told that he had described a quid pro quo arrangement for the military funding, Mulvaney said, "We do that all the time with foreign policy" and later added, "Get over it. There's going to be political influence in foreign policy."

The admission ran contrary to the President's statements -- echoed by his supporters in Congress and the media -- that there was no quid pro quo for the military funding, which had been delayed before ultimately being sent to the Ukrainians. Mulvaney's statement came after current and former Trump administration officials revealed in congressional testimony that a White House meeting between Trump and Ukrainian President Volodymyr Zelensky was also being conditioned on Ukraine launching politically charged investigations.

Mulvaney later denied that he had admitted to the quid pro quo in a written statement. "The only reasons we were holding the money was because of concern about lack of support from other nations and concerns over corruption," he said, adding, "There never was any condition on the flow of the aid related to the matter of the DNC server."

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