Washington DC - Vice Presidentn JD Vance said Thursday that software giant Microsoft was being suspended from a key visa program as part of a fraud crackdown by President Donald Trump’s administration.

Top US universities, including Harvard, that have long been in Trump’s crosshairs over supposed left-wing bias also face an investigation over alleged visa fraud, said Vance.

Vance, who is widely considered to be the frontrunner for the Republican presidential nomination in 2028, was named by Trump to head an anti-fraud task force earlier this year.

"Our message to Microsoft is: you’re a great American company, but you’ve got to hire great American workers," the vice president told a press conference at the White House.

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His announcement came hours before Trump -- who has himself been accused of unprecedented corruption while president -- was to award Microsoft CEO Satya Nadella the most prestigious US technology medal at a ceremony in Washington.

Vance accused Microsoft of abusing the H-1B visa program for highly-skilled foreign workers, saying they had "laid off 6,000 American workers while replacing them with 6,300 H-1Bs."

Microsoft pushed back, saying the "vast majority" of its US employees were Americans and that it looked forward to providing the administration with more information.

The company said that of the roughly 6,000 H-1B applications it filed in the last fiscal year, 80 percent were to extend or change the status of existing Microsoft employees rather than to hire new staff.

The remaining filings were for people already legally in the United States who chose to join the company, and amounted to just one percent of its US workforce, Microsoft said.

"They are not new arrivals to our country," the company said, adding that it paid its H-1B employees the same as other staff doing comparable work.

Software firm Adobe was also being suspended from the visa program, Vance said.

Trump has compared Vance to legendary 1920s law enforcement agent Eliot Ness of the "Untouchables" after a series of fraud probes that have often targeted Democrat-run states and migrant communities.

Republicans hope the issue will resonate with voters ahead of midterm elections in November, in which the Iran war and the cost of living could cost the party its control of Congress.