Negotiations to avoid another government shutdown appear to have stalled, just days before the Friday deadline.

The top four negotiators on the conference committee are set to meet Monday afternoon, in an effort to restart the talks.

Sen. Richard Shelby, Sen. Patrick Leahy, Rep. Kay Granger and Rep. Nita Lowey are scheduled to meet at 3:30 p.m., according to a House Appropriations Committee spokesperson.

Democratic lawmakers want to put a cap on the number of Immigration and Customs Enforcement detention beds. They say the cap will force the Trump administration to focus on arresting and deporting violent criminals, instead of undocumented immigrants who are otherwise following the law.

On Friday, lawmakers were optimistic that a deal would be announced on Monday to give the full House and Senate time to send the bill to the President Trump’s desk by the Feb. 15 deadline.

But on Sunday, Republican Sen. Shelby, the Chairman of the Senate Appropriations committee, told Fox News talks “stalled” over the proposed detention bed cap.

“I’m not confident we’re going to get there. I’m hopeful we’ll get there,” Shelby told Fox News.

Republicans argue limiting the number of immigrants ICE can detain will put Americans’ safety at risk.

Trump tweeted about the dispute over the weekend, saying Democratic lawmakers are “behaving, all of the sudden, irrationally.”

In a tweet on Monday the president said: “The Democrats do not want us to detain, or send back, criminal aliens! This is a brand new demand. Crazy!”

Democratic Rep. Lucille Roybal-Allard, a member of the conference committee, said in a statement that the proposed cap would not allow violent criminals to be released.

“For far too long, the Trump administration has been tearing communities apart with its cruel immigration policies. A cap on ICE detention beds will force the Trump administration to prioritize deportation for criminals and people who pose real security threats, not law-abiding immigrants who are contributing to our country,” said Roybal-Allard in the statement.

Lawmakers also need to nail down funding for barriers along the border.

According to a Democratic aide, negotiators were considering between $1.3 billion and $2 billion for barriers. The aide said in order to finalize funding for barriers, lawmakers need to agree on the ICE detention bed issue.

Shelby told Fox News the odds of the committee agreeing on a deal were 50-50.

Sen. Jon Tester, a Democratic member of the conference committee, struck a more optimistic tone in an interview with Fox News on Sunday.

“Nobody wants a shutdown. Nobody wants the president to use some kind of emergency powers. We just need to do our job and we can do it,” he said. “Every negotiation, almost every negotiation out there hits bumps in the road... but as long we we stay focused in a bipartisan way, bicameral way to get this done -- I’m hopeful we can get this done. Is it a done deal? No, it isn’t. And we could end up in a trainwreck. It’s happened before. But I don’t think anybody has an appetite for a shutdown,” said Tester.