In powerful testimony to the House January 6 committee, a former spokesperson for the Oath Keepers militia told Americans to “quit mincing words and just talk about truths”, and to recognise that Donald Trump attempted to mount “an armed revolution” in order to stay in power.

“People died that day,” Jason van Tatenhove said. “Law enforcement officers died, there was a gallows set up in front of the Capitol. This could have been the spark that started a new civil war, and no one would have won there. That would have been good for no one.”

Van Tatenhove appeared at a Tuesday hearing in Washington alongside Stephen Ayres, a former Trump supporter from Ohio who pleaded guilty to a misdemeanour charge related to entering the Capitol on 6 January 2021.

Both men discussed former allegiances and lessons learned after Congress was stormed by a mob that Trump told to “fight like hell” in service of his lie that his defeat by Joe Biden was the result of electoral fraud.

Ayres said his realisation Trump lied was akin to having “horse blinders” removed. He also spoke about what his conviction had cost him.

Van Tatenhove described efforts by Stewart Rhodes – the Oath Keepers leader now charged with seditious conspiracy – to hone his public image.

Rhodes “was always looking for ways to legitimise what he was doing,” Van Tatenhove said, “wrapping it in the trappings of, ‘It’s not a militia, it’s a community preparedness team … an educational outreach group, it’s a veteran support group.’

“But again, we’ve got to stop with this dishonesty and the mincing of words and just call things for what they are. You know it, he’s a militia leader. He had these grand visions of being a paramilitary leader.”

Members of the Oath Keepers provided security to Trump allies around January 6 and entered the Capitol.

A bipartisan Senate committee linked seven deaths to the riot, which failed to stop certification of Biden’s win. That toll included police officers who killed themselves after the riot, a total that has since grown by two.

Van Tatenhove said: “The fact the president was communicating whether directly or indirectly … kind of gave [Rhodes] the nod, and all I can do to thank the gods that things did not go any worse.”

Asked what the Oath Keepers saw in Trump, Van Tatenhove said: “They saw a path forward that would have legitimacy. They saw an opportunity … to become a powerful paramilitary force.”

Asked if Rhodes discussed violence against elected leaders, Van Tatenhove gave a chilling answer.

“That went back from the very beginning of my tenure,” he said, of an association which began around a standoff with federal forces in 2014. “One of the first assignments that he brought to me … as a graphic artist … was to create a deck of cards.

“You may remember the conflict in the Middle East where our own military created a deck of cards, a who’s who of key players on the other side they wanted to take out.

“And Stuart was very intrigued by that notion and influenced by it, I think, and he wanted me to create a deck of cards that would include different politicians, judges, up to Hillary Clinton as the Queen of Hearts.

“This is a project that I refused to do. But from the very start, we saw that there was always the push for military training, including courses in that community that went over explosives training. So yeah, it all falls in line.”

Van Tatenhove said his experience showed the US had “gotten exceedingly lucky that more bloodshed did not happen because the potential has been there from the start.

“A loss of life as tragic as that we saw on January 6, the potential was so much more. We have to look at the iconic images of that day, with the gallows set up for Mike Pence, for the vice-president of the United States.”

Trump remains free to run for office, retaining support from half of Republican voters, according to a New York Times poll.

Van Tatenhove said: “I do fear for this next election cycle because who knows what that might bring.”

Calling Trump “a president willing to try to whip up civil war amongst his followers using lies and deceit and snake oil, regardless of the human impact”, Van Tatenhove asked: “What else is he going to do if he gets elected again? All bets are off at that point and that’s a scary notion.

“I have three daughters. I have a granddaughter. And I fear for the world that they will inherit if we do not start holding these people to account.”