President Biden tours SK Siltron, a computer chip factory on Tuesday in Bay City, Mich., with CEO Jianwei Dong. “People want to come and invest here,” Biden said as he toured the factory. “We exported more jobs than products.” Patrick Semansky/Associated Press

BAY CITY, Michigan — President Biden reminded Americans he is a “pro-union” president Tuesday as he toured a technology plant to highlight a $300 million expansion, just a day after he sided with business leaders in asking Congress to pass legislation to stave off a crippling rail strike.

The South Korean company SK Siltron is expected to quadruple its production in the coming years at the plant. It’s the latest in a series of massive foreign investments in the U.S. manufacturing and technology sectors trumpeted by Biden amid a push by his administration to on-shore production of key components and products, after the COVID-19 pandemic pushed long-simmering supply chain issues to the brink.

Biden said, as he often does, that he’s been pro-union his entire career, and he’d talked with SK leaders about how American workers were “the best workers in the world, you’re the most qualified workers in the world.”

“The middle class built America, and unions built the middle class,” he said.

His support of unions is a staple of his speeches from warehouses and construction sites around the county. But on Tuesday, it came as he was appealing to lawmakers to override union concerns to prevent a rail strike after an earlier deal Biden helped broker started to fall through. Four of the 12 unions have refused to ratify the agreement, stalling talks and pushing Biden and congressional leaders to get involved to stop what they have said would be a crippling strike during the holiday season. Eight of the unions have ratified the deal.

Biden met with leaders of both parties shortly before leaving Washington for Michigan, and said he was confident they could avoid a strike. House Speaker Nancy Pelosi, D.-Calif., said they’d put legislation forth Wednesday and Senate Majority Leader Chuck Schumer, D-N.Y., said he’d get a vote “ASAP.”

In Michigan, Jeffery Dukes, a member of United Association Local 85, praised Biden before the president’s remarks at the plant.

“President Biden has been committed since day one to fight for the working families of Michigan and thanks to his leadership, American manufacturing is expanding like never before,” Dukes said, adding there was never a better time to be a union member.

Biden highlighted historic investments in manufacturing, saying “we did so much that no one knows the effects of it yet,” and touted his efforts to lower gas prices.

“It’s part of a broader story about the economy we’re building that works for everybody,” he said.

He has sought to boost his political fortunes with his attendance at groundbreakings and other ceremonies highlighting investments in U.S. manufacturing and technology, as he tried to help Democrats in the 2022 midterms and now as he eyes a repeat run for the White House in 2024.

Biden appeared with Gov. Gretchen Whitmer, a Democrat who just won reelection in a closely watched race. Whitmer’s double-digit margin of victory over Tudor Dixon, a Republican who had denied the 2020 election results, has burnished her standing within her party.

“People want to come and invest here,” Biden said as he toured the factory. “We exported more jobs than products. Now we’re back in the business of exporting products, not jobs.”

Later this week, Biden will host French President Emmanuel Macron for the first state visit of his administration.