GM said in a statement it remains focused on “finding solutions to address outstanding issues.”

“Our goal remains to reach an agreement that rewards our employees and allows GM to be successful into the future,” a spokesperson said in a statement.

Securing some guarantees amid the ongoing transformation from internal combustion engines to electric ones has been a top priority for the UAW in its negotiations with GM, Stellantis and Ford, and the concession will likely add pressure on the other two to follow suit.

It also is likely to be welcome news at the White House, which has been fending off union criticism of the EV transition President Joe Biden has been promoting.

“Because of our power GM has agreed to lay the foundation for a just transition,” Fain said.

The UAW’s announcement serves as an olive branch of sorts to the automakers, as well as at least a momentary respite for the White House and Democrats representing auto-producing regions, who support the workers’ demands while quietly fearing that an extended strike could hurt the economy and their political prospects heading into 2024.

“The fact that GM has agreed to that is huge,” Rep. Pramila Jayapal (D-Wash.), the chair of the Congressional Progressive Caucus, told POLITICO. “To be able to have labor on our side with some real certainty and security around their jobs in this transition to a fossil fuel-free environment and EVs is just huge on multiple levels.”

Still, Fain cautioned that the union could reverse course and resume escalating its strike — which stands at 25,000 of the UAW’s nearly 150,000 members across the Big Three — if negotiations hit speed bumps.

“We don’t strike for the hell of it,” he said. “The Big Three know we are not messing around and they know if they want to avoid more strikes, they will have to pony up.”

While much of the union’s focus is on traditional issues like wages and benefits, Fain called GM’s agreement on battery production a “major breakthrough.”

Former UAW President Bob King, who said he was in the room during Fain’s announcement, said GM CEO Mary Barra sent over a copy of the agreement so Fain had it in writing.

The emotion in the room was “just really ecstatic,” King said in an interview. “This is such an important issue to the long term viability and power to get good contracts for the membership, to have the battery plants in the master agreement.”

Fain laid out the union’s perspective on where things stand overall with the latest offers from each of the car companies. In a break from tradition, the UAW has been trying to negotiate with all three simultaneously, rather than focusing its attention on one and then using the resulting deal as a template with the other pair.

Automakers have at times taken issue with the union’s tactics and said that UAW leadership has been slow to engage with their offers — implying that Fain may be stretching negotiators a bit thin.

The timing of GM’s offer was similar to one by Stellantis last week on cost-of-living raises and strike policies. That late-breaking proposal, just before Fain was scheduled to speak, was one of the factors that allowed the Europe-based parent company of Chrysler and Jeep to dodge that round of strike expansions.

Ford has generally been viewed as the most likely of the three to cut a deal first with the UAW, though it has also upset the union by laying off some 1,300 non-picketing workers and attributing it to the disruption caused by the strike. GM and Stellantis have also laid off several thousand workers combined at various plants since the strike began.

But Fain praised GM following its latest offer, saying that it had been “falling behind” the other two but has since “leapfrogged the pack.”

The carrot-and-stick approach has been faring well for UAW, in Fain’s estimation.

“In just three weeks we’ve moved these companies more than anyone thought was possible,” he said.

Fain has been buoyed by outside political support — including an unprecedented picket line visit from President Joe Biden, even as he has tried to keep negotiations from becoming a partisan football. Nevertheless former President Donald Trump, the current Republican frontrunner, also ventured to Michigan for a rally, hoping to draw part of the spotlight to his campaign.

Holly Otterbein and Olivia Olander contributed to this report.