Announcing his second bid for US Senate in Missouri, Lucas Kunce needed to hit the ground running. He did so by running an ad targeting the Republican he hopes to defeat, Josh Hawley, for running away from the January 6 rioters he encouraged.

The ad appeared on the second anniversary of the deadly attack on the US Capitol by Donald Trump’s supporters. On 6 January 2021, before the mob broke in, Hawley was photographed raising his fist in its direction. The House January 6 committee showed what happened after rioters breached the walls: the senator ran for cover.

Hawley has insisted he is “not gonna run” from his political opponents. But Kunce’s ad, showing a fleeing man in a ripped suit, entitled simply Running, attracted national attention.

A self-described populist in the midwestern tradition of President Harry S Truman, Kunce told the Guardian the ad “goes back to the reasons why I’ve run the campaign.

“What I want to do is change who has power in this country, and take some back for everyday people. Folks in Missouri, they’re tired of career politicians like Josh Hawley just doing things for power for themselves and not caring about Missouri and not caring about the country.

“And so that’s why we launched on January 6. It was a seminal moment where Josh Hawley showed he only cares about power for himself. He doesn’t stand for anything. He gets out there when he thinks it’s gonna get him some sort of political power, he’s raising his fist, he’s ‘rah-rah-ing’ the crowd, trying to incite them to do things. And then the second things get real, he’s getting out the back door, running as fast as he can to get away. It shows what a fraud and a coward he is.”

Kunce is a military veteran who also worked on international arms control. In his new ad, as in conversation, he takes aim at Hawley’s contention that America has forgotten what it means to be a man, an argument the senator will make at length in May with a book, Manhood: The Masculine Virtues America Needs.

Kunce said: “As a marine who ran missions in Iraq, deployed to Afghanistan twice, if any of us had shown that type of cowardice [that Hawley showed on January 6], we would have been court martialed.

“Missourians deserve better than someone who’s just going to run. They deserve someone who’s gonna stand for them, fight for them, and that’s what I’m gonna do.”

The Hawley campaign responded to the Kunce ad by wielding the most obvious attack line back: Kunce has lost once in Missouri already.

An adviser said: “We welcome this desperate woke activist to yet another political race. He just barely finished losing his last one. Maybe he’s running in the wrong state.”

Kunce said Hawley’s camp was “obviously worried” because the senator, though thought to be eyeing the Republican presidential nomination, “has never had to run after showing everybody what a fraud and a coward he is. Now he’s got to deal with that.”

In Missouri in 2022, the Democratic primary decided who would run for an open Senate seat as the Republican Roy Blunt retired. Kunce lost to Trudy Busch Valentine, a member of the Anheuser-Busch brewing dynasty who was then beaten by Eric Schmitt, the Republican attorney general, in the general election.

Asked what he learned, Kunce said he had “shown people that no matter how hard it is, I’m not going to take money from the wrong folks. I’m only going to owe the people that took care of my family, everyday Missourians.

“We took no money from corporate Pacs, no federal lobbyists, no big pharma, no big fossil fuel executives. The list is pretty long. And we did that because we want to show that in America everyday people, an everyday person like me, who doesn’t come from connections, doesn’t come from money, can get elected and can do it without corrupting themselves. It’s an uphill battle, but I think it’s worth it.

“Josh Hawley does understand that when he got elected, he took millions of dollars from banks who wanted to control him. His dad was the president of the bank, he had all sorts of connections. And we provide a very good contrast to that.”

Kunce raised more than $5m in 2022 but Valentine, who would ultimately spend more than $16m of her own money, won comfortably. Kunce said: “What we learned in the primary was that money is critical in this political environment. And so we had to figure out a way to raise money without selling out.”

He says “we did that. By the end, we had a record-breaking grassroots fundraising operation. And the beautiful thing is that all that work we did last time, none of it’s gone. The people are still there behind us. We’re growing it out even more, so we’re going to be very formidable this time. We have an operation that can run us all the way through November [2024].”

In most minds, Missouri is a solidly red state. Asked why he thinks a Democrat can win there, Kunce cited recent ballot measures including “expanding Medicaid, increasing the minimum wage $5 over the federal level, passing medical and then recreational legalisation of marijuana, overturning right to work” anti-union laws.

These, he said, were all “things that Josh Hawley did not stand for, that I do stand for. And … Missourians are willing in those situations to flip their vote.

“In 2016, probably the reddest year of all time in Missouri, Donald Trump won here by 17 points. But the Democratic US Senate candidate, Jason Kander, he came within three points of winning.

“I think we’re trending in the right direction. We just need to be able to capture the energy of everyday people trying to take back power for themselves, which clearly is my mission, and which we’ll be able to do.”