President Donald Trump’s “Buy American and Hire American” executive order last year appears to have led federal immigration officials to deny more requests for the controversial H-1B visa, according to a new report.

The H-1B, intended for highly skilled foreign workers and heavily used by Silicon Valley’s technology industry, has become a flashpoint in the debate over immigration, with critics pointing to reported abuses and claiming holders of the visa take jobs from Americans.

Now, the non-profit research institute National Foundation for American Policy is reporting that denial rates for the H-1B shot up significantly toward the end of last year. And this year, officials were continuing to nix applications for skills-based visas at a high rate, the institute reported. It said the upswing in denials was “likely due to new Trump administration policies.”

The H-1B denial rate jumped to 22 percent in the last quarter of the last fiscal year, from 16 percent in the third quarter, a 41 percent increase, according to the institute, which said its findings were based on data from U.S. Citizenship and Immigration. The institute also said its conclusion that denial rates for skills-based visas were high so far this year was based on interviews with lawyers and companies, plus other data.

Denials of H-1B applications started to rise soon after President Donald Trump issued the “Buy American and Hire American” executive order in April 2017, the institute said.

Trump’s order said the U.S. will “rigorously enforce and administer the laws governing entry into the United States of workers from abroad.”

Data suggest H-1B denials rose as Trump administration political appointees began guiding the decisions of visa adjudicators at U.S. Citizenship and Immigration, according to the institute.