Donald Trump is considering testifying in front of the House January 6 committee, which this week concluded a dramatic hearing establishing what it says is his culpability for the deadly Capitol attack by voting to subpoena the former president.

On Friday, sources close to Trump confirmed to the Guardian that he may choose to appear before the congressional panel. Such an appearance would set up an unprecedented, high-stakes political event.

Trump, meanwhile, issued an angry and rambling public letter to Bennie Thompson, the Mississippi Democrat who chairs the January 6 committee.

Since June, Thompson’s committee has laid out in extraordinary detail the chaos, fear and violence of a day now linked to nine deaths.

Regardless, under the title “Peacefully and Patriotically”, Trump reeled off a string of abuse, lies, unsubstantiated claims and outright conspiracy theories about the 2020 election and January 6.

In a predictably intemperate introduction, Trump said the presidential election of 2020 “was rigged and stolen”. It was not. He also cited the Russia investigation (over 2016 election interference and links between Trump and Moscow); “Impeachment Hoax #1” (his impeachment for blackmailing Ukraine for political dirt); “Impeachment Hoax #2” (for inciting the Capitol attack); “the atrocious and illegal spying on my campaign” (a debunked claim); “and so much more”.

He called the members of Thompson’s committee “highly partisan political hacks and thugs whose sole function is to destroy the lives of many hard-working American patriots”.

Nancy Pelosi, the House speaker, rejected Republican attempts to place Trump allies on the January 6 committee, including congressmen implicated in his attempt to overturn the 2020 election, the fuel for the Capitol attack.

Two anti-Trump Republicans, Liz Cheney and Adam Kinzinger, sit on the panel. Testimony presented has been overwhelmingly from Republicans and members of Trump’s White House and administration.

Trump has sent cease-and-desist letters to media outlets including the Guardian that call him a liar in print. Nonetheless, his letter rehashed his big lie about election fraud, appendices listing debunked claims about Arizona, Pennsylvania, Georgia and Michigan, key states in Joe Biden’s conclusive win.

In an echo of Trump’s famous refusal to admit that the crowd for his inauguration in 2016 was smaller than that for Barack Obama in 2008, the former president also exaggerated the size of the crowd which heard him speak near the White House on January 6 – the speech in which he told supporters to “fight like hell”.

Returning to another favorite subject, the former host of NBC’s Celebrity Apprentice concluded: “Despite very poor television ratings, the unselect committee has perpetuated a show trial the likes of which this country has never seen before.

“… You have not gone after the people that created the fraud, but rather great American patriots who questioned it, as is their constitutional right. These people have had their lives ruined as your committee sits back and basks in the glow.”

More than 900 people have been charged in relation to the Capitol attack. Many have been jailed. Members of the Oath Keepers and Proud Boys far-right groups are charged with seditious conspiracy. Both groups have been linked to Trump aides and allies, prominently including the Republican operative Roger Stone, who was shown on film in Thursday’s hearing saying: “Fuck the voting, let’s get right to the violence.”

Peter Navarro and Steve Bannon, aides to Trump, face jail time for contempt of Congress, after refusing to cooperate with the January 6 committee.

But though the panel made clear on Thursday that it holds Trump responsible for the insurrection, he has not been held to account.

If Trump refused to comply with the subpoena issued by the committee – which seeks testimony and documents – he too could be charged with contempt of Congress.

But that seems unlikely, given both his position as former president, de facto leader of the Republican party and possible 2024 presidential nominee, and the proximity of the midterm elections. If Republicans take back the House next month, as seems likely, the January 6 committee will in all probability be disbanded.

Trump hinted at that outcome in his letter, writing: “The people of this country will not stand for unequal justice under the law, or liberty and justice for some. Election day is coming.”

Knowing this, committee members may be hoping the subpoena draws Trump out, luring him into public testimony about his attempt to overturn an election.

Committee members have said that while they do not expect to make criminal referrals to the Department of Justice, they have sought to lay out their findings in a way that may help federal investigators.

After the midterm elections, the attorney general, Merrick Garland, will have at least two more years to decide whether to indict Trump related to January 6.

In a tweet after Thursday’s hearing, Kinzinger, of Illinois, said: “We just voted unanimously to subpoena Donald Trump. Our democracy demands it. Our constitution demands it. The truth demands it.”

Laurence Tribe, a Harvard law professor, said: “This final hearing was the most effective in years. Taken together with the committee’s prior hearings, it left no doubt that Trump deliberately tried to steal the 2020 election and committed major federal crimes in the process.”