Former Congressman Michael Grimm pleaded guilty to one count of tax fraud in 2015.

That scandal is playing a starring role in his successor's first campaign ad:

"Inmate 83479053: convict Congressman Michael Grimm," a narrator says in part of New York Rep. Dan Donovan's add.

The congressman, who represents Staten Island and parts of Brooklyn, released his first radio ad of the primary season on Tuesday, going on the attack, hitting Grimm for his prison stint and tax bill. It ticks off some of the allegations in Grimm's indictment, claiming Grimm was guilty of those too.

"20 counts of fraud: guilty. Perjury: guilty. Hiring illegal aliens: guilty," a narrator says in the Donovan ad.

Grimm said the ad is false. He sent us a statement saying, in part: "...The hardworking people of this district know the truth: I hired a few delivery boys off the books, I was a very effective and hardworking Congressman, and these outlandish lies only highlight the pathetic end of Donovan's career."

The Grimm campaign said it will file cease and desist letters with radio stations playing the ad, and file a complaint with the New York Bar Association against Donovan personally.

It's just the latest controversy in what's become a nasty race.

Last month, Donovan was accused of using his influence to make sure his girlfriend's son didn't spend a night in jail after a heroin arrest. He denied having any sway, blaming dirty politics instead.

Donovan had told NY1 he would release his phone records to prove it.

"I don't know how to get my phone records, but you can look at my phone records. I never made a call, and certainly I found out about Tim's arrest well after he was released," Donovan said on April 2.

But Donovan told us this week that he is backing away from that commitment:

"I've refused to talk about it and I've refused to respond to my opponent about this any longer. We are not doing this in the media," Donovan said.