When Working Families Party state committee members gather at their convention tomorrow, far more than the endorsement for governor will be at stake.

The very future of the labor-backed party will be on the line, and according to one labor source, the damage done by the disagreement over whether or not to back Gov. Andrew Cuomo again may very well be irreparable.

“Regardless of what happens now, the way the party has conducted itself has done lasting damage to relationships with key (union) affiliates,” the source said. “It’s unclear if the party will ever be the same.”

Union leaders were burning up the phone lines this morning, discussing whether the time had finally come to pull their support of the party they helped create and have financially sustained since 1998.

According to another labor source involved in these talks, a number of the largest and most significant unions – including 1199 SEIU, HTC, the laborers, RWDSU, and the UFT – were prepared to call it quits with the WFP, knowing that their withdrawal could very well lead to the party’s “collapse.”

The Teamsters and TWU were also involved in these discussions, which were far enough along to warrant talk of drafting of a joint statement, although one was never actually released.

The problem is not merely that these unions and others have benefitted from their relationship with Cuomo and want to give him Row D as payback. There is something bigger in play – the direction in which the party has been going and its overall reason for existing in the first place.

The reality is that creation of a public campaign finance system – an issue of utmost importance this legislative session to the activist faction of the WFP – is not actually all that important to many labor unions, which care more about job creation, wages and benefits.

Or, as one labor leader told me this morning, the “far left progressive agenda” that is driving the party at the moment “does not put one person to work.”

As Capital NY reported this morning, about one third of the WFP’s state committee seats are vacant – a situation that empowers the activists over the union members.

The anger that was palpable among union officials this morning seems to have calmed somewhat, and they are now holding off on the so-called “nuclear option” of pulling out of the WFP altogether.

But that possibility is still on the table, according to these sources, and will remain there even if the divided state committee endorses Cuomo over Fordham Prof. Zephyr Teachout tomorrow, or decides to back a placeholder candidate for governor on the line for the short term.

At least one labor source suggested that creation of an entirely new party has been discussed – one truly focused on the needs of “working people” and not interested in striking a symbolic blow in New York to capitalize on a perceived national moment of political power for the left.

It was also suggested that perhaps the New York City-based unions could choose to redirect their support to the Central Labor Council, empowering it to become more of a political player, though it would not – as the WFP does (for the moment) – have the benefit of a ballot line.

It’s also possible that an eleventh-hour deal comes together, with NYC Mayor Bill de Blasio managing to cobble together some sort of temporary peace agreement between labor, the WFP leadership, and the governor that would be amenable to the party’s rank-and-file.

But even if that happens, unions might not be so inclined to support the WFP going forward, being slightly less generous in their contributions to its coffers and less enthusiastic in encouraging their members to cast general election votes on the WFP line.

The situation at the moment is very fluid, and could very well remain so right up until the voting at the convention on the endorsement for governor question begins tomorrow night.

And, according to BuzzFeed, Cuomo is reportedly fanning the flames by asking AG Eric Schneiderman – a darling of the left – to refuse the WFP’s endorsement, which would be a significant blow.

The governor may have made the same ask of state Comptroller Tom DiNapoli, who arguably owes his close 2010 win over Republican Harry Wilson to the unions and the GOTV effort they ran on his behalf.