Hatch will offer an amendment on the Senate floor to require immigrants to show they have paid income and employment taxes over the years, placing the burden of proof on the applicant rather than the IRS, where it currently lies.

The current language, in contrast, essentially gives immigrants applying for legal status a pass on back taxes unless the IRS already has an outstanding liability in their names. And the only way the tax-collecting agency would have those records is if immigrants have already filed tax paperwork such as a W-2.

Critics of the bill’s current approach contend many immigrants are paid under the table and have no IRS paper trail, so back taxes under the legislation wouldn’t apply to them unless the IRS has already identified the applicants as in the red and owing money.

At least one Republican in the Gang of Eight, Sen. Marco Rubio of Florida, is open to changing the bill.

“We do support Hatch’s efforts to address this issue,” Rubio spokesman Alex Conant said in an email.