"It's simply wrong to think that we're in a totally open world and that any American with a job can be replaced if somebody in the world is willing to take a job for less pay," Senator Jeff Sessions told members of Senate Judiciary Committee during his confirmation hearing for the position of US Attorney General.
Trump has made tougher immigration policy a central theme since the day he announced he would run for president.
In the past, both Sessions and Grassley have worked together to bring legislations on H-1B visas that badly hit Indian IT companies.
The Office of Special Counsel for immigration related unfair employment practices is an office within the Justice Department which would be headed by Sessions if he is confirmed by the US Senate.
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"While the office is designed to protect foreign nationals with employment visas from discrimination, it is also charged with ensuring that American workers are not discriminated against in the workplace.
Many US workers advocate that the layoff of American workers and the replacement by cheaper, foreign, H-1B workers constitutes de facto nationality based discrimination against American workers," Grassley said.
"The Obama administration has failed to protect American workers here. Will you, this is my question, will you be more aggressive in investigating the abuses of these visa programmes?" he asked.
Describing Sessions as a vocal champion for American workers, Grassley said many American workers are being laid off and replaced by cheaper foreign labour imported through some of the US visa programmes.
Sessions, Grassley and Senator Dick Durbin in the past had co-sponsored a bill that would reform H-1B visa programmes by ensuring that qualified American workers are considered for high skilled job opportunities before those jobs can be offered to foreign nationals.