Senators next week will take up the nearly impossible task of finding the votes to pass a bill that protects younger illegal immigrants from deportation while improving border security and reforming the nation’s immigration policies.

There is no guarantee Senate lawmakers can pass any immigration reform bill, given the partisan differences, but Majority Leader Mitch McConnell, fulfilling a promise he made to both parties last month, plans to give lawmakers a shot at it.

McConnell scheduled a vote Monday on a revenue bill that would serve as a legislative vehicle for an immigration proposal that can win 60 votes, which is the requisite number needed to advance legislation and end debate on it. But the substance of the immigration bill is up in the air.

“The bill I move to, which will not have underlying immigration text, will have an amendment process that will ensure a level playing field at the outset,” McConnell said early Friday morning. “The amendment process will be fair to all sides, allowing the sides to alternate proposals for consideration and for votes. While I obviously cannot guarantee any outcomes, let alone supermajority support, I can ensure the process is fair to all sides. And that is what I intend to do.”

McConnell promised an immigration debate in exchange for Democrats dropping a demand that federal spending legislation passed this week include a provision to protect so-called Dreamers from deportation.

With spending fights out of the way after months of bickering, McConnell said lawmakers can introduce immigration legislation and offer their proposals as amendments to the shell bill.

Minority Leader Chuck Schumer, D-N.Y., called it “a neutral bill” that will allow “an opportunity for a bipartisan compromise focusing on the Dreamers and border security that has a real chance of getting 60 votes.”

Lawmakers are likely to debate several proposals, among them a framework sent to Congress by President Trump, who triggered the debate by announcing an end to the Obama-era Deferred Action for Childhood Arrivals program.

The DACA program protects young people who came here illegally as children and who many have labeled Dreamers. Trump rescinded DACA and gave Congress until March 5 to find a legislative solution.

Trump has proposed permanent legal protection and a pathway to citizenship for 1.8 million Dreamers, but in exchange, he wants significant funding for border security, including funding for a southern border wall. Trump is also demanding an end to extended chain migration and the visa lottery system.

It's not clear any bill can pass without a political agreement between the two parties. But in the meantime, the Trump administration is publicly pressuring the Senate to pursue the president’s framework. The Justice Department has been publishing weekly reports on criminals who arrived in the U.S. through the visa lottery system or chain migration.

“Time to end the visa lottery. Congress must secure the immigration system and protect Americans,” Trump tweeted last week, linking to a DOJ report on a visa lottery entrant who violated sanctions against Iran.

But Trump’s plan would likely meet with a filibuster from the Democrats, who oppose changes to the current extended chain migration policy, which they say is a form of family unification.

A bipartisan group of senators has introduced a more moderate immigration proposal, which would legalize Dreamers and end the visa lottery system. The plan, authored by Sens. Lindsey Graham, R-S.C., and Dick Durbin, D-Ill., would limit chain migration, but it would include relatives beyond minor children and spouses, which is the new limit conservatives and Trump are seeking. The Graham-Durbin plan includes $2.7 billion for border security – a fraction of the $25 billion Trump wants for a border wall system – and security improvements at ports of entry.

Trump has publicly rejected the proposal.

Trump favors provisions in a bill introduced by Sens. Tom Cotton, R-Ark., and David Perdue, R-Ga., that would reform the green card program and cut legal immigration by half.

Like the Graham-Durbin proposal, the Cotton-Perdue plan has little chance of passing without changes.

The lack of a viable bill means the debate next week will be freewheeling and unpredictable.

Lacking a consensus plan, Senate Republicans and Democrats have been meeting for weeks, clumped in different factions throughout the Senate.

Trump administration officials have been part of the talks. They’ve participated in meetings with the minority and majority leaders in both chambers, but both parties admit the discussions have not advanced any concrete plan.

Sen. Susan Collins, R-Maine, has also been conducting meetings on what is likely to be a more moderate proposal, although nothing specific has emerged yet.

Sen. James Lankford, R-Okla. told the Washington Examiner that the pressure is now on lawmakers to produce a bill.

“We’ve got to get this all worked out and establish how this is going to be done,” Lankford said. “I really do believe it can be done.”

Senate passage of an immigration reform bill would put intense pressure on the House to take up the measure. But so far, Speaker Paul Ryan, R-Wis., is siding with Trump. He told reporters last week he would bring up legislation the president will sign, rather than passing a more moderate measure.

Conservatives are pressuring GOP leaders to bring up legislation authored by House Judiciary Committee Bob Goodlatte, R-Va., that would provide protections for Dreamers, but no pathway to citizenship. It would end chain migration and the visa lottery system.

“I’m confident we can bring a bipartisan solution to the floor that can get signed into law, and solve this problem,” Ryan said last week. "We want a DACA solution. We want an immigration solution. I'm confident we can get there.”