California Rep. Eric Swalwell says he was “punched” in the shoulder by an airline passenger who demanded that Democrats begin impeaching President Trump.

Swalwell tweeted that the interaction happened early Monday while he was boarding a United Airlines flight.

“A passenger boarding the @united plane I’m on just stopped in front of me, punched my shoulder, and said ‘you all better get your act together and impeach him,’” Swalwell said.

A passenger boarding the @United plane I’m on just stopped in front of me, punched my shoulder, and said “you all better get your act together and impeach him.” — Rep. Eric Swalwell (@RepSwalwell) September 23, 2019

House Democrats who have not supported impeaching the president appear to be moving toward doing so after the revelation of a whistleblower complaint about a phone call between Trump and Ukrainian President Volodymyr Zelensky. Trump reportedly urged Zelensky eight times to work with his personal attorney, Rudy Giuliani, on an investigation into Hunter Biden, the son of Trump’s potential 2020 rival Joe Biden.

[Related: ‘Start impeachment on Friday’: Intelligence Committee Democrat calls for immediate action against Trump if whistleblower complaint is withheld]

Trump acknowledged to reporters on Sunday that he did discuss Biden with Ukraine’s president: “The conversation I had was largely congratulatory, with largely corruption, all of the corruption taking place and largely the fact that we don’t want our people like Vice President Biden and his son creating to the corruption already in the Ukraine.”

House Speaker Nancy Pelosi, who has been hesitant to move forward on impeachment, warned that Joseph Maguire, the acting director of national intelligence, refusing to hand over the complaint to Congress could make impeachment more likely.

“If the Administration persists in blocking this whistleblower from disclosing to Congress a serious possible breach of constitutional duties by the President, they will be entering a grave new chapter of lawlessness which will take us into a whole new stage of investigation," Pelosi wrote in a letter to colleagues on Sunday.

House Intelligence Committee Chairman Adam Schiff said Sunday that impeachment could be the “only remedy” if Trump pressured Ukraine.

Even if the Democratic-controlled House impeaches Trump, the Senate, where Republicans hold the majority, is unlikely to convict Trump to remove him from office.