WASHINGTON, Aug 10 (Reuters) - Republican Congressman John Moolenaar, who leads the House Select Committee on China, called on the Trump administration to make sure chip manufacturers don't send advanced logic chips to untrusted Chinese firms.

In January 2025, the Biden administration unveiled a new rule requiring chip manufacturers to scrutinize orders of advanced chips from companies that could be serving as a front for untrusted firms from China and other countries.

The rule was a response to revelations that Chinese chip designer Sophgo had chips manufactured at TSMC that were later discovered inside AI processors marketed by Huawei. Huawei has been heavily sanctioned by the United States.

Soon after President Donald Trump took office, though, his administration announced it did not plan to enforce another Biden-era chip regulation referenced in the manufacturer rule, fueling uncertainty about the enforcement of that measure.

In a letter dated Thursday, Moolenaar described the measure as "a critical step in preventing [China] from accessing high-end U.S. chips and preserving America's technological edge," urging the Commerce Department to enforce it.

The chip manufacturer rule was created "to close the loophole that Huawei and Sophgo exploited," Moolenaar wrote in the letter, sent to Jeffrey Kessler, who oversees export controls at the Commerce Department.

If chip factories like TSMC, the world's largest, determine that their chips are not subject to the rules, "it would dramatically increase the risk of another SophGo-like export control failure," Moolenaar said.

Commerce, Huawei, Sophgo and TSMC did not respond to requests for comment.

The letter, not previously reported, is a sign of increasing congressional concern, even among Republicans, about the Trump administration's more lenient approach to advanced chips reaching Chinese shores.

In June, Republican Senator Jim Banks co-wrote a letter urging Trump's administration to tighten rules on chip contract ​manufacturers to prevent them from ‌making advanced AI chips for overseas units of Chinese companies.

Republican Representative Bill Huizenga sharply criticized Kessler over similar concerns last month, while a decision by the Trump administration to allow Nvidia ( NVDA ) to sell advanced AI chips to China has drawn fire from both parties.