As President Trump addressed Congress last week, he veered off script to attack a sensitive topic, the CHIPS Act, a bipartisan law aimed at making the United States less reliant on Asia for semiconductors.

Republican lawmakers had sought and received reassurances over the past few months that the Trump administration would support the program Congress created. But halfway through Mr. Trump’s remarks, he called the law a “horrible, horrible thing.”

“You should get rid of the CHIP Act,” he told Speaker Mike Johnson as some lawmakers applauded.

The CHIPS program was one of the few things to unite much of Washington in recent years, as lawmakers on both sides of the aisle worked with private companies to draft a bill that would funnel $50 billion to rebuild the U.S. semiconductor industry, which makes the foundational technology used to power cars, computers and coffee makers. After President Joseph R. Biden Jr. signed it into law in 2022, companies found sites in Arizona, New York and Ohio to construct new factories. The Commerce Department vetted those plans and began to dole out billions of dollars in grants.

Now, Mr. Trump is threatening to upend years of work. Chip company executives, worried that funding could be clawed back, are calling lawyers to ask what wiggle room the administration has to terminate signed contracts, said eight people familiar with the requests.

After the speech, Senator Todd Young, the Indiana Republican who championed CHIPS, said he reached out to the White House to seek clarity about Mr. Trump’s attack because the criticism was “in tension” with the administration’s previous support.