WASHINGTON — A Republican lawmaker who's been a leading advocate of striking a bipartisan immigration deal is guarded about whether the Senate can approve a compromise on the politically electric issue, days before the chamber is expected to begin a debate that looms as an unpredictable free-for-all.

"I don't know. Right now, it's tough to see," Sen. Jeff Flake, R-Ariz., said Thursday about whether any proposals will get the 60 GOP and Democratic votes needed to survive.

Flake told reporters he thinks President Donald Trump "sees a political downside of not fixing" the problem of "Dreamers," younger immigrants whose protections against deportation the president is ending. But he says Trump "is only willing to go so far" because of his conservative base.

Flake recounted what Trump privately told GOP lawmakers after a White House meeting the president had with Congress' two top Democrats, Senate Minority Leader Chuck Schumer and House Minority Leader Nancy Pelosi. Schumer and Pelosi emerged from that meeting saying Trump had agreed to work toward an agreement to protect the Dreamers, only to see the White House take a less yielding stance.

"He flatly said to us, 'I had the meeting with Chuck and Nancy but then the base went crazy,'" Flake said.

Because Trump's positions can veer wildly, Republicans have at times urged the White House to minimize the president's role on some issues. Flake said "those messages have certainly been sent" on the upcoming immigration debate.

Flake is retiring next year and has sharply criticized Trump for having authoritarian tendencies.

Flake said he's working on one proposal that would ease parts of the immigration plan Trump unveiled last month. Trump's plan unchanged cannot get 60 votes, he said.

Trump would offer a route to citizenship for up to 1.8 million young immigrants in the U.S. illegally in exchange for border security money, including funds for his coveted U.S.-Mexico border wall, plus curbs on legal immigration. Flake suggested he would let legal immigrants continue to be able to sponsor their parents for permanent residence, which Trump would halt, and would not cut overall legal immigration levels. An aide later said Flake hadn't made final decisions about his proposal.

As a fallback, Flake said he'll propose extending young immigrants' protections for three years and providing three years' worth of border money.

Trump said in September he was terminating President Barack Obama's Deferred Action for Childhood Arrivals program, or DACA, which temporarily lets hundreds of thousands of Dreamers live and work in the U.S. He's given Congress until March 5 to resuscitate it, though a federal court has blocked its termination for now.