WASHINGTON – House Speaker Nancy Pelosi accused President Donald Trump of having a "temper tantrum" over Democratic investigations Wednesday and suggested his Rose Garden blowup was about politics more than infrastructure.

"Sadly, the only job the president seems to be concerned with is his own," Pelosi wrote in a letter to lawmakers released to reporters. "He threatened to stop working with Democrats on all legislation unless we end oversight of his administration and he had a temper tantrum for us all to see."

Trump disputed that characterization in a tweet late Wednesday.

"This is not true. I was purposely very polite and calm, much as I was minutes later with the press in the Rose Garden," Trump wrote. "Can be easily proven. It is all such a lie!"

Trump informed Democratic leaders that he wouldn't work with them on shared priorities such as infrastructure unless they abandoned investigations into his presidency. In an unexpected appearance in the Rose Garden, Trump said he told Pelosi and Senate Minority Leader Charles Schumer that it would be impossible to go forward on discussions while "phony" congressional investigations hang over his administration.

"We’ve had a House investigation. We have Senate investigations. We have investigations like nobody has ever had before," Trump told reporters after leaving the meeting on infrastructure. "And there’s nothing – we did nothing wrong."

Trump spoke specifically about ending talks on infrastructure, but it was difficult to see how the White House would work with the Democratic-controlled House on other issues, such as prescription drugs or a pending trade agreement with Mexico and Canada, during the feud.

Cover up?Pelosi says Trump's 'cover-up' could be 'an impeachable offense'

No deal:Trump to Democrats: No deals on infrastructure until investigations over

Earlier in the day, Pelosi said that the president "is obstructing justice and he is engaged in a cover up and that could be an impeachable offense." Pelosi issued another statement on Wednesday evening – after the letter to colleagues – defending the House probes and repeating the "cover-up" term

"The president must honor the Constitution and the rule of law, and provide the information we need to find the truth for the American people," Pelosi said. "We will continue to follow the facts, wherever they take us.”

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