A Democratic senator appeared on CNN to accuse President Donald Trump of colluding with Russia during the campaign and obstructing justice afterward — and the president lashed out minutes later.

Sen. Richard Blumenthal (D-CT) told CNN’s “New Day” that a grand jury investigation could turn up evidence of serious wrongdoing by the president and his campaign associates involving Russian interference in the 2016 campaign.

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“It was purposeful and relentless, and it involved propaganda and hacking into our machines or at least an attempt to do it and potential collusion by the Trump campaign and then obstruction of justice,” Blumenthal said. “That investigation must be pursued.”

About 10 minutes later, the president tweeted a response from the start of his 17-day “working” vacation.

Interesting to watch Senator Richard Blumenthal of Connecticut talking about hoax Russian collusion when he was a phony Vietnam con artist! — Donald J. Trump (@realDonaldTrump) August 7, 2017

Blumenthal has admitted he had “misspoken” about his Marine Corps service during the Vietnam War, and Trump — who did not serve in the military — has called for an investigation of the senator’s wartime service following previous criticisms.

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“Never in U.S.history has anyone lied or defrauded voters like Senator Richard Blumenthal,” Trump tweeted Monday morning. “He told stories about his Vietnam battles and. conquests, how brave he was, and it was all a lie. He cried like a baby and begged for forgiveness like a child. Now he judges collusion?”

…conquests, how brave he was, and it was all a lie. He cried like a baby and begged for forgiveness like a child. Now he judges collusion? — Donald J. Trump (@realDonaldTrump) August 7, 2017

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Trump insisted, just minutes before reacting to Blumenthal’s television appearance, that he was working from his New Jersey golf club while the White House underwent renovations.

Working hard from New Jersey while White House goes through long planned renovation. Going to New York next week for more meetings. — Donald J. Trump (@realDonaldTrump) August 7, 2017

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He spent much of the morning tweeting complaints about negative media coverage.