In a chilling warning, a conservative judge closed the the third January 6 committee hearing on Thursday by saying Donald Trump, his allies and supporters were still “a clear and present danger to American democracy”.

J Michael Luttig testified that the former US president and his Republican supporters are preparing in open sight an “attempt to overturn that 2024 election in the same way that they attempted to overturn the 2020 election, but [to] succeed”.

The retired federal judge, a Ronald Reagan appointee, testified in his capacity as an adviser to Mike Pence, who was vice-president to Trump between 2017 and 2021.

In a statement before the hearing, Luttig said: “A stake was driven through the heart of American democracy on January 6 2021, and our democracy today is on a knife’s edge.

“America was at war on that fateful day, but not against a foreign power. She was at war against herself. We Americans were at war with each other – over our democracy.”

The hearing which followed focused on efforts by Trump and advisers to convince Pence to block certification of Joe Biden’s victory, Pence’s refusal to do so and the deadly attack on the US Capitol which put Pence in danger.

Closing the hearing, Bennie Thompson of Mississippi, the Democratic committee chair, asked Luttig to say what he meant by calling Trump and his supporters a clear and present danger.

Luttig said: “Almost two years after that fateful day … Donald Trump and his allies and supporters are a clear and present danger to American democracy.”

“That’s not because of what happened on January 6. It is because to this very day the former president and his allies and supporters pledge that in the presidential election of 2024, if the former president or his anointed successor as the Republican party presidential candidate were to lose that election, they would attempt to overturn that 2024 election in the same way that they attempted to overturn the 2020 election, but succeed in 2024 where they failed in 2020.”

According to the Washington Post, more than 100 Republicans who have won primaries for midterm elections this year back Trump’s lie about electoral fraud in 2020. Such candidates have targeted key state elections posts as well as governors’ mansions and seats in Congress.

Trump was impeached over the Capitol attack but acquitted of inciting an insurrection when only seven of 50 Republican senators found him guilty. He has strongly suggested he will run again.

Luttig said: “I don’t speak those words lightly. I would have never spoken those words ever in my life. Except that’s what the former president and his allies are telling us … the former president and his allies are executing that blueprint for 2024 in the open, in plain view of the American public.”

“I repeat, I would have never uttered one single one of those words unless the former president and his allies were candidly and proudly speaking those exact words to America.”