TALLAHASSEE — Republican leaders said Wednesday that they won't approve a budget by the scheduled end of the legislative session in 15 days because of a showdown over Medicaid expansion.

Asked by reporters if he agreed that it was already too late to meet their deadline, House Speaker Steve Crisafulli, R-Merritt Island, said he did.

"I would assume most likely we're looking at a special session," Crisafulli said.

Senate Appropriations Chairman Tom Lee, R-Brandon, also said he thought it was too late to end on time and that a special session, rather than extending the regular session, was likely.

"The sand is running out of the hourglass as we speak," Lee said. "Until there's some remedy, some breakthrough, some epiphany, we're at an impasse."

Even though the session is scheduled to end May 1, state law requires that the final budget be on the desks of lawmakers 72 hours before they vote on it. That moves up the deadline to wrap up budget negotiations to April 27, giving lawmakers little more than a week to bridge a $4 billion gap between the Senate and House proposed budgets.

But neither the House nor Senate seem ready to back down. Lee suggested that positions are hardening.

"As the session progresses and the opportunity to bring this in for a landing in 60 days appears to be extinguishing at this moment, pressure mounts and people react differently," Lee said. "You're starting to see a more defensive posture being taken. I've encouraged everybody to maintain their decorum."

A special session can be convened any time after the regular session ends, allowing lawmakers to return home before coming back to Tallahassee at a later date to pass a budget, which goes into effect July 1.

The last time lawmakers didn't approve a budget on time was in 2009, when Charlie Crist was governor. Lawmakers extended the session one week to come to agreement.

This year's impasse centers around health care funding.

Lawmakers are currently looking at a $1.3 billion budget hole because the federal government has said it will not continue a hospital funding program known as the Low Income Pool. In a letter to the state Medicaid office Tuesday, federal health officials said they would be willing to consider a potential successor program proposed by the Senate, but no deal has been reached.

Making matters worse, the House and Senate are at odds over Medicaid expansion. The Senate wants to accept $2 billion in federal funds to expand private health care coverage to low-income Floridians. The more conservative House does not.

The letter from the U.S. Centers for Medicare and Medicaid Services on Tuesday made it clear that the two policies are linked. That is, if Florida expands coverage, the state will be more likely to have its LIP funds renewed. Still, the House remains unwilling to budge.

"Up until yesterday, Medicaid expansion and LIP were never put together," Crisafulli said Wednesday. "They were never related issues. Now the federal government has put them together. That's a change in position on their part."

Lee said the federal government has always linked the two, and rightly so.

"They've told me personally that there's a direct correlation between the uninsured in Florida and the level of unreimbursed care," Lee said. "There is no absolute one-to-one correlation between those two, but there is a substantial correlation between the two. That's not news to anybody."

On Wednesday, state Agency for Health Care Administration Secretary Liz Dudek told a Senate panel she wasn't sure whether CMS would approve the revised LIP program Florida had proposed — or how much money Florida was likely to get. At one point in the negotiations, Dudek said, the federal government said Florida might only receive half of the money it received last year.

She also conceded that there was no formal Plan B.

Other recent developments have further complicated budget negotiations. Enrollment for K-12 has surged in recent months, which is estimated to cost an additional $100 million next year.

"We need to build a budget that's realistic," Lee said. "We're getting more bills than revenue right now."

The Senate made its position clear Wednesday, when Dudek was up for a confirmation hearing before the Senate Ethics and Elections Committee. The panel voted 8-1 to support her reappointment, but only after grilling her about the LIP program and Medicaid expansion for more than an hour.

During a series of tough questions, former Senate President Don Gaetz, R-Niceville, called a Senate proposal to extend LIP "the only life raft available." He and others repeatedly suggested that expanding health care coverage to poor Floridians would help hospitals deal with the potential loss of LIP funds.

The Senate also kept the pressure on Republican Gov. Rick Scott, who recently changed his position and voiced opposition to Medicaid expansion.

Senate President Andy Gardiner, R-Orlando, spoke to Scott by telephone Wednesday, telling him that the Senate supports his priorities: tax cuts and more money for schools.

"They had a cordial conversation," said Sen. Garrett Richter, R-Naples, who was listening in Gardiner's office. "The president indicated that we're anxious to get a budget and we'd like to do it on time, and we're anxious to get a budget that responds to the (health care) issues — and we've got the tax cuts on the shelf. We're also supportive of the education funding that the governor wants to do. But before we decide how to do it, we've got to get this big elephant tamed. There's a $2 billion elephant in the room."

Crisafulli gave no indication that the House would consider a plan that included an expansion of Medicaid.

"This is where we stood in the House for as far as I can remember on Obamacare," Crisafulli said. "For us, we've just won six House seats on an issue that's very argumentative. ... There are people from this chamber that aren't here anymore because they believe so heavily in that issue. The electorate would probably appreciate where we stand on the issue."

Times/Herald staff writer Steve Bousquet contributed to this report.