Within a couple days of the meeting, Benson released a long list of local endorsements for his campaign. Martin — whose town is the most populous in Mercer County — and Cimino were on the list. Norcross’ insurance company, Conner Strong & Buckelew, abruptly dropped Cimino’s engineering firm as client, according to the people familiar with the meeting.

The meeting was arranged by Drennan, a Hamilton resident with close connections to the South Jersey Democratic machine due to his years as the top aide to former Senate President Steve Sweeney (D-Gloucester). Despite that, Drennan, who’s close to Martin and Cimino, is also considered to be a Benson supporter.

The endorsements were a rare rebuke to Norcross, the son of a labor leader who, beginning in the early 1990s, built New Jersey’s most formidable Democratic political machine, forged alliances across party lines and grew Conner Strong & Buckelew into a business that has drawn in public and private sector clients from New Jersey and beyond.

In a statement, Norcross acknowledged the meeting but said Cimino wasn’t forthright with him.

“Kevin Drennan arranged a meeting among friends to better understand the outlook of the county executive race. We shared our views and left amicably and honorably. Three of us told the truth on where we stood,” Norcross said. “One person, John Cimino, proved to be a bald-faced liar. One day after our meeting where he pledged he would be neutral he reversed his position and made an endorsement.”

One of the clients Norcross’ firm represents is Mercer County’s insurance fund. Another was T&M Associates, a politically connected engineering firm and one of the state’s major political donors where Cimino is an executive.

Shortly after the December meeting, Conner Strong ended its relationship with T&M, according to those familiar with the meeting. According to a report from InsiderNJ, Steve Ayscue, Norcross’ chief political consultant, also severed his relationship with T&M around the time of the meeting.

Cimino declined to comment, and a phone call to T&M Associates was not returned.

The dispute shows how intense the county executive race has gotten, and how its political ramifications have spilled beyond Mercer County, where Democrats control all countywide offices but do not have a single power broker who dominates local politics like Norcross does in much of South Jersey.

Because of this factionalization, the county executive race is threatening to spill into other contests around Central Jersey. In December, Hughes told POLITICO that if he doesn’t secure the powerful “county line” for the Democratic primary, he may put together his own slates of candidates for state Legislature.

“Some people want me to put the lines together and put up a fight. I’ve got some legislators who are willing to run with me,” Hughes said at the time, declining to name them. “Let me just end it there. If you want to be viable, you’ve got to be in that second column.”

Earlier this month, some Mercer County residents were polled by an unknown group about a potential state Senate primary between incumbent Linda Greenstein (D-Middlesex) and her longtime running mate, Assemblymember Wayne DeAngelo (D-Mercer), according to New Jersey Globe. DeAngelo told the publication he supports Greenstein, but the fact that someone’s polling the races shows insiders are at least preparing for the possibility for a wider fight.