Two measures headed to the Senate floor could reopen an immigration debate that left the chamber bitterly divided this past summer.

The outcome of the votes will likely determine whether the 110th Congress can move any measures that could pave a pathway to citizenship for any of the nation’s estimated 12 million illegal immigrants.

“I think the Dream Act is a litmus test,” said Sen. Robert Menendez (D-N.J.), a Cuban-American who supports the plan. “If we can’t do this for children ... then I doubt we can do anything else.”

Both measures have bipartisan support, but are vigorously opposed by conservatives who say such legislative efforts amount to “amnesty” for illegal immigrants. If the supporters reach the 60 votes needed to proceed to the Dream Act, it could become a vehicle for other competing amendments and reignite debate on a comprehensive overhaul of immigration policies, which the Senate rejected by a 46-53 vote in June. A similar situation could occur with the so-called agriculture jobs measure.

But Democrats are hoping to avoid that situation and keep the debate to both helping students and retaining farm workers.

“We’re going to try to make this very focused,” said Majority Whip Dick Durbin (D-Ill.), who is sponsoring the bill. “I don’t want to reopen the comprehensive immigration bill debate in all of its different areas that could come up. Really I just want to test this issue.”

Much like this summer’s immigration debate, moving forward with the measure has the potential to split the Republican caucus. Senate Republican Conference Chairman Jon Kyl (R-Ariz.), one of the architects behind the bipartisan immigration bill, has advocated creating a pathway to citizenship for the 12 million illegal immigrants and adding new enforcement measures along the U.S.-Mexico border. But on Tuesday, he said he was not sure whether he would vote to proceed to debating the Dream Act, saying Democrats were changing the bill and he had yet to see its contents.

“It’s a moving target,” Kyl said.

Other Republicans kept open the possibility of supporting the measure, including Sen. John Cornyn of Texas, who defied the White House earlier this year by voting to block the comprehensive overhaul in the summer.

But the leader of his caucus, Sen. Mitch McConnell (R-Ky.) opposes the Dream Act, as do two leading GOP senators who helped derail the broad overhaul bill this year, Jeff Sessions of Alabama and Jim DeMint of South Carolina.

Sessions warned that he would bury the bill with amendments if cloture is invoked on Wednesday. He said if Democrats try to use procedural tactics to block amendments, the measure will have the same fate as the broader overhaul.

“I think it’s going to be a whole big mess” if Wednesday’s vote is successful, Sessions said.