Six months out and the field seeking the United States Senate seat is set — First Lady Tammy Murphy and Rep. Andy Kim for certain and incumbent Bob Menendez perhaps.

It’s unlikely a fourth viable candidate will emerge, one with substantial financial and organizational support and the wherewithal to mount a competitive campaign. New Jersey’s Congressional Democrats have all taken a pass on surrendering their safe seats to take on a scandal weakened Menendez, an almost certain loser who faces even odds on whether he’ll even seek re-election while under indictment on Federal corruption charges.

Of equal interest in the candidate competition is the proxy war shaping up between the Democratic Party’s entrenched establishment —- most of which has already endorsed Murphy — and a range of active political and civic groups who reacted furiously to the immediate surge of endorsements and the implicit intention to place her on the ballot with the slate of candidates favored by the county organizations — the so-called county line.

She’s received the endorsements from county chairs in Hudson, Bergen, Essex, Camden, Middlesex, Passaic and Somerset, as well as the majority of the state’s congressional delegation.

She was immediately installed as the front runner on the strength of the promised ballot positioning, a not unreasonable response given the long history of primary election success enjoyed by candidates who receive the endorsement.

The county line — used freely by both parties — has been attacked and defended over the years but has survived and thrived and absent a court ruling to end the practice will continue to do so.

Gov. Murphy, for instance, used it to great advantage in his initial run for governor in 2017 by doling out financial help to county organizations in return for securing the line, effectively ending the gubernatorial ambitions of Jersey City Mayor Steve Fulop and former State Senate President Steve Sweeney.

While Kim is certainly a formidable candidate, experienced and qualified, he faces a daunting task to overcome the power of the county line.

By endorsing Murphy, the county chairs have placed their reputations on the line as well, understanding that their power and authority relies on their ability to deliver in the clutch.

For them, success is mandatory in a highly visible public endorsement in an equally high-profile contest, particularly one involving the state’s political and governmental leader.

Failure is not an option, nor is the potential embarrassment of attempting to explain why they fell short and admitting their leadership was ignored.

Added to the imperative to deliver on their pledges, county leaders are keenly aware of the need to maintain a cordial working relationship with Gov. Murphy for the remaining two years of his term.

He may be a lame duck, but for two more years he will decide on major legislation, control distribution of state aid as well as approve patronage and major appointments including judgeships, boards and commissions.

For those frustrated and angry over the concerted attempt to — in their words — fix an election, there is little recourse.

County leaders will not willingly surrender one of the few remaining and powerful political weapons at their disposal and the courts will continue to be reluctant to involve the judicial process in settling internal political differences.

History suggests also that while the county line is often an issue, once election returns are in, interest diminishes, replaced by other more pressing needs.  It has never been a compelling issue among the broader electorate.

The Kim campaign will find it difficult, indeed, to convince the already committed county leaders to back away or to ease the pressure on their organizations to deliver a pro-Murphy voter turnout.

The Camden organization endorsement will impact adversely Kim’s support in his South Jersey base and the Murphy endorsement by a majority of his Congressional colleagues — while not seriously harmful — is decidedly unhelpful.

For Kim, the open lane for him is narrow and obstacle strewn, but not insurmountable.  Issues do matter in primary contests, even though outweighed by money, organizational strength and troops on the ground.

Kim possesses the edge in an issue-oriented campaign, but his familiarity, insight, policy knowledge and vision may not be sufficient.

While Menendez has rebuffed all demands that he resign, he has remained circumspect about seeking another term.  Realistically, though, he’s irrelevant with zero support and a public approval standing of five percent.

In its history, New Jersey has elected one — one! — woman statewide — Christie Whitman as governor in 1993.  Many of the progressive groups who seek to abolish the county line process have long decried this lack of representation — and rightly so.

It is ironic that the opportunity to correct that historic imbalance may be delivered through a process they profess to despise as anti-democratic and perpetuating backroom boss politics.

The most recent data shows Democratic Party voter registration at just over 2.5 million, the pool from which Murphy and Kim will seek support.

At a healthy 40 percent turnout, slightly more than one million party faithful will choose a Senate candidate and, in the process, settle —-temporarily at least — the proxy war between the party establishment and the reform-minded progressives.

First one to half a million will plant the flag.

Carl Golden is a senior contributing analyst with the William J. Hughes Center for Public Policy at Stockton University.