Denver’s mayoral candidates accused each other of bending the truth on Tuesday in an escalating volley of charges surrounding a TV ad that calls one of them a liar.

After Mike Johnston’s campaign reiterated demands that TV stations stop airing an ad released last week by an outside group supporting his opponent, Kelly Brough, her campaign fired back, distributing a statement from a former government official that took issue with multiple fact checks by local news outlets that describe the ad as “botched” and “misleading.”

At issue is a 30-second spot from A Better Denver 527, a super PAC backing Brough, that accuses Johnston of “lying about his leadership” during the COVID pandemic and a decade ago in the state Senate when Democrats passed landmark gun control legislation.

The ad, which has been running on local broadcast, cable and streaming platforms since May 18, contends that Johnston has repeatedly exaggerated his role in the controversial issues, but Johnston’s campaign counters that it’s the super PAC that’s mischaracterizing both what he’s said and what happened.

“Mike Johnston – all talk, no leadership,” the ad’s narrator says.

“I’ve fact-checked hundreds of ads over the last 14 years, and I’m not sure I’ve ever seen one as botched as this, which is astounding given the seriousness of the claims,” CBS4 political reporter Shaun Boyd said in a “reality check” aired by the station on Monday.

Mail ballots went out to Denver voters a week ago and are due back by June 6. The winner of the runoff election will take over for outgoing Mayor Michael Hancock, who is term-limited.

On Tuesday afternoon, Brough’s campaign distributed a statement from the former director of Colorado’s COVID-19 Innovative Response, Sarah Tuneberg, who denounced Johnston for trying to take credit for “the public servants who actually did this work,” referring to the state’s rollout of its massive COVID testing and vaccination program.

“This is about Mike Johnston’s lies and exaggerations,” Tuneberg says in a lengthy Facebook post. “It is about his lack of ethics and what that means in a role like Mayor.”

The ad attacking Johnston’s credibility features a brief clip from an earlier TV news interview with Tuneberg making similar points.

Johnston’s campaign contends, however, that he’s only ever taken credit for the award-winning COVID testing project he spearheaded when he ran the Denver-based nonprofit Gary Community Ventures, an initiative called COVIDCheck – a program Tuneberg called a “great organization” and acknowledged in her statement “did a ton of testing.”

But while COVIDCheck was one of numerous vendors involved in Colorado’s response to the pandemic, she added, the work she and her team did was “orders of magnitude more complex, intense, high pressure, and innovative.”

The ad also accuses Johnston of overstating his role in passing 2013 gun safety measures when he was a state senator, citing an earlier news report that noted Johnston wasn’t a primary sponsor of any of the bills that passed.

In response, Johnston’s campaign rolled out supportive statements from fellow former lawmakers, including state Sen. Rhonda Fields, D-Aurora, who endorsed Brough earlier this month but backed up Johnston’s contention.

“He was directly engaged with Senate members on Gun bills. He voted ‘Yes’ for a safer Colorado!” said Fields. “Ending gun violence is too serious to become a political football in Denver’s 2023 Mayoral race.”

As of late Tuesday, the local TV stations airing the outside group’s ads had yet to respond to a cease-and-desist letter sent by the Johnston campaign on Friday, a campaign spokeswoman told Colorado Politics.

“The truth is that Mike has never lied about his accomplishments and it is A Better Denver’s ad that is untrue,” wrote Sarah Mercer, the campaign’s attorney. “The ad makes several false claims about Mike that are clearly and objectively disprovable.”

An attorney representing the super PAC called on the stations to disregard the demand, arguing that the ad “essentially echoes reporting by 9News” and noting that 9News “does not dispute the veracity of the statements made in the ad” in its own story about the ad.

9News political reporter Marshall Zelinger, however, disputed the ad’s conclusions in a “truth test” aired by the station on Monday.

“This political ad paid for by supporters of Kelly Brough makes this inaccurate statement, and then tries to use my reporting to back it up,” Zellnger says in the segment, which calls the ad “misleading.”

“I reported on Denver mayoral candidate Mike Johnston’s resumé. I never said he lied,” Zelinger says, referencing clips excerpted in the ad. Then, citing another statement by the ad’s narrator, Zelinger adds: “‘Johnston says he built Colorado’s COVID testing program.’ No. He never said that. And our story never claimed that.”

Lynea Hansen, the registered agent for A Better Colorado 527, told Colorado Politics on Tuesday that the group stands by its ad.

“One thing that has been overlooked in all this – how we cut the ad or not, a lot of folks are talking about how Mike Johnston takes credit for things other people have done, and I don’t think that has been disputed,” she said. “He continues to exaggerate, and continuing to exaggerate is lying about what you achieved.”