Daniel Bongino, the Republican running for U.S. Senate in Maryland, said Monday he has fired off a complaint to the Federal Election Commission accusing independent candidate Rob Sobhani of making an illegal robocall.

The Sunday evening call violated federal campaign law by failing to included required disclaimers that disclose the identity of its backer and the source of its funding, Bongino said. Bongino, in an interview, said the call also speaks to a broader pattern of deceit in Sobhani’s campaign.

“He’s just a liar. And a fraud,” Bongino said. “He’s everybody to everyone, and so he’s nobody to anyone.”

The Sobhani campaign acknowledged Monday that the substance of the robocall message was theirs. But campaign spokesman Sam Patten also said the robocall was produced with the required disclaimers. He said that the recordings that upset Bongino lack disclaimers either because they were sent inadvertently or were doctored by someone to try to embarrass the Sobhani campaign.

The FEC complaint is the latest jab in an increasingly nasty brawl for second place in the U.S. Senate campaign in Maryland.

Bongino and Sobhani are running against Sen. Benjamin L. Cardin (D). Polls suggest that Bongino and Sobhani are also splitting the anti-Cardin vote, thereby ensuring Cardin’s reelection in a race he was favored to win. Sobhani, a Potomac businessman, has made a bigger splash than other unaffiliated or third-party candidates on the ballot, at least partly because of the millions he has spent on campaign ads.

Sunday’s disputed robocall includes a 36-second message from “Mary,” who calls herself a “a lifelong conservative Republican in Maryland.”

The substance of her message declares that Sobhani supports declaring English as the official language and claims that Bongino does not. Such a measure is under consideration in Carroll County; similar measures have been passed in Frederick and Queen Anne’s counties, both of which have more Republican voters than Democrats.

“You know, we conservatives can finally beat Ben Cardin if we vote for the real conservative in this race,” the message says. “So don’t waste your vote. Let’s elect a real conservative. Elect Rob Sobhani for U.S. Senate.”

Patten said that the campaign was taking a shot at Bongino only because the Republican has spent a lot of time attacking Sobhani.

“We haven’t been focusing on Dan Bongino. But we have noticed that Dan Bongino is focused on Rob Sobhani,” Patten said Monday.

Over the weekend, the Sobhani campaign also accused Bongino of strong-arming Republican speakers who participated in a teleconference call aimed at likely Republican voters. The call focused on several questions on the ballot, such as the DREAM act, which would give in-state tuition rates to the college-bound children of illegal immigrants. Among others, the participants included Del. Neil Parrott (R-Washington) — who helped put questions about the Dream Act and gay marriage on the November ballot — and Sobhani.

Sobhani’s campaign said afterwards that the call’s participants were “strong-armed” by Bongino to make it clear that they were not in Sobhani’s camp.

“They were told their name would be mud in the Republican Party unless they disassociated themselves from the Rob Sobhani,” Patten said.

But Bongino denied the accusation.

“It’s just more Sobhani nonsense,” Bongino said. He said Sobhani had been trying to sell the conference call as an implicit endorsement by its participants of Sobhani’s campaign. Bongino said Parrott has given him an unequivocal endorsement.

As for Sunday’s disputed robocall, Bongino said it fits with other vague, contradictory and questionable claims from Sobhani.

Bongino, whose wife is a U.S. citizen who immigrated from Colombia, said he would back the idea of English as the official language in government documents and the like, but he also said that the topic of English-as-official-language is not something anyone has asked him about or publicized during the campaign.

“I think he just made it up,” Bongino said.