United States autoworkers are expanding their two-week strike to additional locations, with the head of a major union saying 7,000 more workers will join the picket lines as labour talks have failed to advance significantly.

United Auto Workers (UAW) President Shawn Fain said in a video appearance on Friday that negotiations have not broken down but Ford and General Motors “have refused to make meaningful progress”.

The strike will expand to Ford’s Chicago assembly plant and GM’s assembly plant in Lansing, Michigan, at midday on Friday, said Fain, bringing the total number of workers on the picket lines to 25,000. The strike will not include any additional members at Jeep maker Stellantis.

“Sadly, despite our willingness to bargain, Ford and GM have refused to make meaningful progress at the table,” Fain said.

“Let’s stand up and win this thing – for ourselves, for our families, for our communities, for our country and for our future,” the UAW president added.

The union launched the partial, coordinated strike earlier this month, with thousands of workers across 20 states walking off the job to push for wage increases, shorter hours and improved retirement benefits.

The work stoppage has drawn national attention, with US President Joe Biden and his Republican predecessor and likely 2024 election challenger Donald Trump both travelling to Michigan this week to show support for the striking workers.

Speaking from a picket line outside an auto plant west of Detroit on Tuesday, Biden called for a “significant raise” for the employees.

“You made a lot of sacrifices, gave up a lot, and the companies were in trouble,” the Democratic president said, referring to the 2008 financial crisis when US car manufacturers were on the verge of bankruptcy.

“Now they’re doing incredibly well. And guess what? You should be doing incredibly well.”

The UAW is expected to continue work stoppages currently under way until a new contract is ratified, a source familiar with the situation, speaking on condition of anonymity, told the Reuters news agency.

Automakers say the union’s demands would hurt their profits as they try to compete with non-union manufacturers such as Tesla.

The companies’ last known wage offers were around 20 percent over the life of a four-year contract, a little more than half of what the union has demanded.

Other contract improvements, such as cost of living increases, restoration of defined benefit pensions for newly hired workers, and an end to tiers of wages within the union are also on the table.

Progress was reported in talks on Thursday night, especially with Stellantis.

On Friday, Ford CEO Jim Farley said he felt his company could reach a compromise on pay and benefits with the unions. But he accused the UAW of “holding the deal hostage” over Ford’s use of outside companies — with non-union workers — to build batteries for electric vehicles, or EVs.

About 18,300 UAW members at the Detroit Three are currently on strike, or about 12 percent of the 146,000 union members working at the automakers. Strikers have been getting $500 a week from the UAW’s strike fund.

“To be clear, negotiations haven’t broken down. We’re still talking with all three companies and I’m still very hopeful that we can reach a deal,” said Fain, the union president.

“We are fed up with corporate greed and we are fed up with corporate excess. We are fed up with breaking our bodies for companies that take more and more and give less and less.”