WASHINGTON, DC, United States (AP) — The US House January 6 committee voted unanimously Thursday to subpoena former President Donald Trump, demanding his personal testimony as it unveiled a startling new video from close aides describing his multi-part plan to overturn his 2020 election loss that led to his supporters’ fierce assault on the US Capitol.

With alarming messages from the US Secret Service warning of violence and vivid new video of congressional leaders pleading for help, the panel showed the raw desperation at the Capitol. Using language frequently seen in criminal indictments, the panel said that Trump had acted in a “premeditated” way ahead of January 6, 2021, despite countless aides and officials telling him he had lost.

Trump is almost certain to fight the subpoena and decline to testify. On his social media outlet he blasted members for not asking him earlier — though he didn’t say he would have complied — and called the panel “a total BUST”.

“We must seek the testimony under oath of January 6’s central player,” said Republican Representative Liz Cheney of Wyoming, the committee’s vice-chair, ahead of the vote.

In the committee’s 10th public session, just weeks before the congressional midterm elections, the panel summed up Trump’s “staggering betrayal” of his oath of office, as Chairman Bennie Thompson put it, describing the former president’s unprecedented attempt to stop Congress from certifying Democrat Joe Biden’s victory.

While the effort to subpoena Trump may languish, more a nod to history than an effective summons, the committee has made clear it is considering whether to send its findings in a criminal referral to the Justice Department.

In never-before-seen Secret Service messages, the panel produced evidence that extremist groups provided the muscle in the fight for Trump’s presidency, planning weeks before the attack to send a violent force to Washington.

The Secret Service warned in a December 26, 2020 e-mail of a tip that members of the right-wing Proud Boys planned to outnumber the police in a march in Washington on January 6.

“It felt like the calm before the storm,” one Secret Service agent wrote in a group chat.

To describe the president’s mindset, the committee divulged new material, including interviews with Trump’s top aides and Cabinet officials — including Secretary of State Mike Pompeo, Attorney General William Barr and Labour Secretary Eugene Scalia — in which some described the president acknowledging that he had lost.

In one, according to ex-White House official Alyssa Farah Griffin, Trump looked up at a television and said, “Can you believe I lost to this [expletive] guy?”

Cabinet members also said in interviews shown at the hearing that they believed that once legal avenues had been exhausted, that should have been the end of Trump’s efforts to remain in power.