WASHINGTON – An already fierce Republican primary in South Jersey has now picked up allegations of defamation (by one candidate), accusations of bullying (by another) and fake campaign Web sites that disparage one another.

The latest round of back-and-forth began with businessman and former Randolph Mayor Tom MacArthur suing his opponent, Steve Lonegan, for defamation in response to information on one of the sites. Lonegan reacted Tuesday with a Trenton press conference in which he called MacArthur a bully.

"It's this kind of bullying and strong-arming of people that's downright despicable and has no place in this race," said a Lonegan press release tied to the event.

Lonegan pointed to one campaign aide named in the suit who is a single mother.

"I don't trust anyone who would sue a single mother," Lonegan said, according to PolitickerNJ. "You don't do that."

The campaign aide, Elizabeth Curtis, is Lonegan's treasurer and custodian of records. She is one of six campaign staffers, along with Lonegan, cited by name in the lawsuit.

"Steve Lonegan should look in the mirror. This is about his campaign and how they’re conducting themselves,” said MacArthur spokesman Chris Russell. “Steve Lonegan’s putting his own people at risk by running a campaign of lies and dishonesty.”

He said Lonegan is pushing back because of the effectiveness of MacArthur's ads showing that Lonegan spoke out against a federal aid package after Superstorm Sandy, which battered the South Jersey district. Lonegan has said the aid bill was bloated with waste.

MacArthur has twice used his attorneys to take issue with Lonegan's criticism of his performance as an insurance executive. Lonegan's campaign has pointed to three cases in which the insurance firm MacArthur built and led, York Risk Services Group, was sued by claimants saying they had been underpaid.

Alongside news stories about those suits, a Lonegan Web site attacking MacArthur also linked to a report about another suit brought by Phoenix firefighters against York (It's under the link "Sleazy Insurance Salesman"). But MacArthur had already left the company and had nothing to do with the suit, Russell said. MacArthur's lawsuit accuses the Lonegan campaign of "intentionally and maliciously" publishing "false and defamatory" statements.

Earlier, MacArthur had sent Lonegan a cease and desist letter after Lonegan press releases said MacArthur  had been accused of "insurance fraud" – which was not alleged in the lawsuits.

The animosity has extended online and even to Twitter, where staffers for both campaigns on Tuesday argued over who set up their attack sites first. The two sites with innocent sounding names -- MacArthurForCongress.com and MayorLonegan.com – lead to damaging information about the candidates.

You can follow Tamari on Twitter or email him at jtamari@phillynews.com.