The United Auto Workers called off its six-week strike on Monday after union leaders reached a tentative labor agreement with General Motors — the last of the Detroit Big 3 car manufacturers to strike a deal with the union.

"Now that we have a groundbreaking tentative agreement at GM, we're officially suspending our stand-up strike against each of the Big 3," UAW President Shawn Fain said in a video message posted on X (formerly Twitter).

The GM deal features a 25% wage increase across a four-and-a-half year deal with cost of living adjustments, the UAW said. The deal also brings employees from GM's manufacturing subsidary GM Subsystems and Ultium Cells — a battery manufacturing plant GM shares with LG in Ohio — under the UAW national contract.

The deal, which still needs to be ratified, mirrors a tentative agreement UAW leaders reached last week with Ford and Stellantis.

GM confirmed the tentative agreement on Monday, saying the terms will still allow the company to provide good jobs.

"We are looking forward to having everyone back to work across all of our operations, delivering great products for our customers and winning as one team," GM CEO Mary Barra said in a statement.

The deal comes a day after GM workers expanded their strike by walking out of a company factory in Spring Hill, Tennessee, that employs nearly 4,000 and that produces Cadillac and GMC SUVs. Spring Hill joined about 14,000 other GM workers who were already striking at company factories in Texas, Michigan and Missouri.

President Biden said the GM deal attests to the power of unions and collective bargaining.

"This historic tentative agreement rewards the autoworkers who have sacrificed so much with the record raises, more paid leave, greater retirement security, and more rights and respect at work," Mr. Biden said in a statement. "I want to applaud the UAW and GM for agreeing to immediately bring back all of the GM workers who have been walking the picket line on behalf of their UAW brothers and sisters."

GM was the last of the Big 3 to ink a deal with the UAW.

"In a twist on the phrase 'collective bargaining,' the UAW's strategy to negotiate with and strike at the three automakers simultaneously paid off with seemingly strong agreements at all three organizations," Lynne Vincent, a business management professor at Syracuse University and labor expert, told CBS MoneyWatch. "Once a deal was reached at Ford, the UAW could use that agreement as the pattern for the other two automakers, which gave the UAW leverage to apply pressure on the automakers."