Microsoft Corp will favor neither American nor foreign workers as it cuts thousands of jobs, the company said on Tuesday in response to a senator's call that the jobs of U.S. employees be preserved.

Microsoft said in January that it would eliminate up to 5,000 jobs, or about 5 percent of its workforce, surprising investors as it released quarterly results that missed Wall Street expectations.

The news also caught the eye of Republican Sen. Charles Grassley, who fired off a letter asking that Microsoft detail the cuts, while urging the world's biggest software company to preserve the jobs of Americans ahead of foreigners with visas.

Microsoft said it was too early to be precise, but the percentage of workers at the company who hold so-called H-1B visas would remain roughly the same.

We do not expect to see a significant change in the proportion of H-1B employees in our workforce following the job reductions, General Counsel Bradford Smith said in a letter to Grassley.

The Senator said the response left him wanting more details. I'm still left without much information about how Microsoft is ensuring American workers are being protected or specifics of its H-1B visa hiring practices, Grassley said in a statement.

H-1B employees have always amounted to less than 15 percent of Microsoft's U.S. workforce, Smith said in the letter dated March 3.

The potential to tap into the world's best minds has long been essential to our success, he wrote.

Microsoft has been a champion of expanding the H-1B temporary visa program, which lets American companies and universities hire foreign workers in a category the government considers specialty occupations.

The company also said that, including positions to be created, the net impact would be 2,000 to 3,000 fewer jobs.

Grassley, who is the ranking Republican member of the Senate Finance Committee, had asked Microsoft Chief Executive Steve Ballmer to provide a breakdown of the jobs to be eliminated, how many of those are staffed with individuals with H-1B visas and how many with Americans.

(Reporting by Kim Dixon; editing by Lisa Von Ahn and Tim Dobbyn)