A super PAC funded by unions and a progressive group has spent $100,000 on an ad that questions the past business practices of Democratic Montgomery County executive candidate David Blair and compares his mostly self-funded campaign to President Trump’s.

The ad by the Progressive Maryland Liberation Alliance super PAC, which begins airing on Montgomery County cable stations Friday, accuses Blair of “using his big money” to buy the election.

It is the latest demonstration of the effort liberal groups are making to defeat Blair in the June 26 Democratic primary, which is tantamount to the general election in deep-blue Montgomery, Maryland’s most-populous jurisdiction.

Blair is the only nonpolitician among the six Democrats vying to succeed longtime County Executive Isiah Leggett, who is retiring after three terms.

The ad cites a 2012 first-person narrative on the left-leaning blog Daily Kos by a man who accuses Blair’s former company — pharmaceutical benefits manager Catalyst Rx — of profiting by increasing the co-pays on the prescription multiple sclerosis medication used by the author’s mother, a retired Michigan teacher. The ad also accuses another, unnamed former Blair company of selling “virtually worthless disability claims.”

“Montgomery County Democrats: What we see is not what we get,” the narrator says at the end. “David Blair is just not one of us.”

County executive candidate David Blair (D). (Katherine Frey/The Washington Post)

The super PAC — which can accept unlimited donations and make independent expenditures to support or oppose candidates — does not offer any proof that its accusations are true. The group has been distributing fliers at candidate forums containing similar allegations.

Blair has denied the allegations, calling the fliers part of a “smear campaign.” He said Catalyst Rx had a contract with the Michigan Public Schools Employees’ Retirement System to administer prescription benefits, but that his company did not set the co-pays or even decide which drugs the plan would cover. Instead, he said, Michigan system’s board made those decisions.

“Catalyst has nothing to do with pricing,” Blair said in a recent interview. “The allegation that Catalyst was paid more money for higher-priced drugs, or that we set the prices, is false.”

Officials at the Michigan Department of Technology, Management and Budget did not have information about the contract immediately available Friday morning.

Kyle Lierman, Blair’s chief strategist, issued a statement Friday calling the allegations “misinformation, lies and smears.”

“Montgomery County voters know better and want a leader with a vision and a plan to fix our transportation system, improve schools and create jobs to generate the revenue we need to fund our progressive priorities,” Lierman said. “That’s David Blair.”

The super PAC’s June 5 campaign finance filing shows it received $90,000 in late May and early June from four PACs connected to unions — including $35,000 from the PAC of Municipal County Government Employees Organization Local 1994, which represents Montgomery County workers, and $5,000 from SEIU Local 500 D.C. — and $5,000 from CASA in Action.

MCGEO, SEIU Local 500 and CASA all have endorsed council member Marc Elrich (D-At Large), another top contender for the nomination.

“We think there’s a lot more that voters in Montgomery County need to know about the history and track record of David Blair,” said Larry Stafford Jr., who is executive director of the nonprofit Progressive Maryland as well as the super PAC’s chairman. “This is all on the table now, and it’s time for him to answer questions about his past business dealings and his past political affiliations as well.”

Stafford said the ad, which cost $10,000 to produce, will run through the primary. Early voting began Thursday.

It’s not the first televised attack ad against Blair, who has spent nearly $2 million of his own money so far on the race.

One of his five opponents, council member Roger Berliner (D-Potomac-Bethesda), also ran an ad that compared Blair to Trump.