A tetchy congressional primary in the southern half of New Jersey is growing increasingly messy.

Tom MacArthur, who is running for the Republican nomination for New Jersey's 3rd congressional district, has sued his primary opponent, Steve Lonegan, for defamation. And it's not just Lonegan: The lawsuit also names a number of Lonegan's staffers and consultants as defendants.

At issue are statements made by Lonegan's campaign alleging that MacArthur -- who spent 30 years in the insurance industry and was chairman and CEO of an insurance claims service firm -- was accused of insurance fraud and is linked to legal action involving Phoenix firefighters alleging they were denied claims. The MacArthur campaign called those claims false and defamatory and sent multiple cease-and-desist letters to Lonegan's campaign regarding them.

Tim Kelly, a spokesman for Lonegan's campaign who is named as a defendant in the suit, said that the campaign responded to the cease-and-desists by changing the headline of one press release from “MacArthur accused of insurance fraud” to “MacArthur accused of sleazy insurance practices.” Kelly said no other Lonegan communications were changed or removed in response to the letters.

The candidates have both compared each other's behavior to President Obama's.

Lonegan’s campaign called MacArthur a “bully.” Elizabeth Curtis, who works part-time for the Lonegan campaign as its treasurer, wrote an open letter to district voters.

“It's like Obama using the IRS to silence conservatives,” she said in the letter. “Who does this? I don't have money for lawyers like MacArthur does. I have children to provide for.”

Chris Russell, a spokesman for MacArthur’s campaign, said MacArthur's lawyers advised him to sue the campaign as a whole as well as name individual staffers as defendants.

“That’s how the attorneys thought it was best to file the suit,” he said. “And we’ll find out who was involved in doing all this.”

“He’s the one launching these attacks, and now he’s trying to point fingers at Tom MacArthur?” Russell continued. “If Steve Lonegan didn’t lie and didn’t try and defame Tom MacArthur, he wouldn’t be in this situation.”

“It's interesting to see someone like Steve Lonegan, who claims to be such a free enterprise conservative, whose attacks at this point sound a lot like Barack Obama's attacks on Mitt Romney,” he added.

When asked in a follow-up email if MacArthur would drop the suit if it doesn’t come to trial before the June 3 primary, Russell wrote, “Tom is serious about protecting his reputation and isn’t going to let Steve Lonegan or the Democrats get away with lying about him without being held accountable.”

The suit has drawn criticism from prominent conservative commentator Erick Erickson, who wrote on May 20 that MacArthur was using “lawfare” against Lonegan.

Lonegan, a Tea Party favorite, ran against Cory Booker in the 2013 special election to fill the seat for many years by Sen. Frank Lautenberg. MacArthur is former mayor of Randolph, N.J., a township in the northern part of the state with a population of about 25,000.