Schumer said the purpose of crossing the aisle to vote on legislation that he and most Democrats opposed in its current form was so it could hopefully be amended before final passage.

“Democrats want to have a robust debate, where we can offer amendments and improve the bill,” Schumer said on the Senate floor. “To remind my colleagues: this is not a vote on the bill itself. This is a motion to proceed, a vote that says we should have a debate and should have amendments.”

The vote will require the backing of 60 senators, including at least eight Democrats. The bill, which passed the House earlier this week with bipartisan support, was expected to easily clear the first of several hurdles thanks to significant backing from Democrats.

The measure would require federal authorities to detain illegal immigrants charged with theft-related crimes until deportation and empower states to sue the Department of Homeland Security for harm to citizens caused by illegal immigration.

WHAT TO EXPECT FROM TRUMP’S MASS DEPORTATION PLAN

Dubbed the Laken Riley Act, the proposal is named after the 22-year-old Augusta University nursing student who was killed last year by a Venezuelan illegal immigrant while jogging at the University of Georgia.

Two Senate Democrats — Ruben Gallego (D-AZ) and John Fetterman (D-PA) — have gone so far as to co-sponsor the legislation. However, while Republicans will win over a number of Democrats on the first procedural vote, the process to reach final passage and send it to the president’s desk is far from over.