WASHINGTON (TIP): A popular visa program allegedly is being misused by U.S. companies to lay off thousands of American workers and replace them with foreign labor.

And, adding insult to injury, many of the laid-off workers allegedly have been forced to train their replacements, in what one anonymous whistleblower called a “humiliating” experience.

The allegations have caught the attention of a bipartisan group of senators — including immigration hawk Sen. Jeff Sessions, R-Ala., and the No. 2 Senate Democrat, Illinois’ Dick Durbin — who are calling for a federal probe. A letter sent by 10 senators urging an investigation specifically cited reports of the firing and hiring practices at Southern California Edison, California’s second-largest utility. The incidents are concentrated in the IT field, and involve American workers being replaced by H-1B visa holders.

“A number of U.S. employers, including some large, well-known, publicly-traded corporations, have reportedly laid off thousands of American workers and replaced them with H-1B visa holders,” the senators wrote. In the letter to Attorney General Eric Holder, Homeland Security Secretary Jeh Johnson, and Labor Secretary Thomas Perez, the senators urged the departments to “investigate the unacceptable replacement of American workers” to see whether laws were broken.