The negotiations from the conference committee developing a border-security proposal to avert another government shutdown have stalled.

The committees' top Senate and House members are meeting to rescue the talks.

Funding for a large portion of the federal government runs out on February 15.

WASHINGTON — Top Republicans and Democrats on the conference committee tasked with crafting a border-security proposal by the February 15 funding deadline are meeting Monday in an attempt to rescue the faltering negotiations.

Democrats have taken issue with the number of detainees that Immigration and Customs Enforcement (ICE) can house, citing a difference between undocumented immigrants without previous criminal records and those with them.

The breakdown over that dispute, among other factors, has greatly increased the likelihood of another partial government shutdown or the declaration of a national security emergency by President Donald Trump in order to start the construction of additional physical barriers on the US-Mexico border

Read more: Another government shutdown looms as funding runs out in a week and Democrats are still undecided about Trump's border wall

Republican Sen. Richard Shelby of Alabama and Democratic Sen. Patrick Leahy of Vermont will convene with their House counterparts on the conference committee, Republican Rep. Kay Granger of Texas and Democratic Rep. Nita Lowey of New York.

Shelby gave a grim assessment of the negotiations during an interview on "Fox News Sunday with Chris Wallace."

"I think the talks are stalled right now," Shelby told Wallace. "I’m hoping we can get off the dime later today or in the morning because time is ticking away, but we’ve got some problems with the Democrats dealing with ICE, that is detaining criminals that come into the US, and they want a cap on them. We don’t want a cap on that."

"I'm not confident we're going to get there," Shelby added. "I'm hoping we will get there."

The dispute holding back the negotiations is over how many detention beds ICE can have for apprehended immigrants, including those with criminal records. Republicans believe the number should not be capped and that ICE should have the ultimate say on the matter.

Sen. Jon Tester of Montana, one of the Democrats on the conference committee, told Wallace that he is "not positive we'll to end up with a deal," but that they can deal with "the challenges we have on the southern border in a common sense way."

Members of the conference committee were previously feeling "cautiously optimistic" about being able to reach an agreement, which Rep. Henry Cuellar, a Democrat, predicted would be finished by last Friday. But negotiations have stalled, and now the threat of another shutdown is inching closer by the day.

Trump is holding the threat of an emergency declaration over Congress' head

If Trump makes good on the threat to circumvent Congress and declare a national emergency to get funds for the wall, he will likely do so with significant Republican support, despite some lawmakers having publicly questioned its legality.

House Minority Leader Kevin McCarthy told reporters on Friday that Republicans would not join a resolution of disapproval for making an emergency declaration. McCarthy also said, "I don't think anyone questions his legal authority to declare a national emergency."

But even the president's close confidants, such as South Carolina Sen. Lindsey Graham, have expressed legal concerns over such action.

And Rep. Mac Thornberry of Texas, the top Republican on the House Armed Services Committee, characterized an emergency declaration as out of form.

"In short, I am opposed to using defense dollars for nondefense purposes." he said. "Seems to me we ought to fund border security needs on their own and not be taking it from other accounts."

Still, Trump is forging ahead with the threat to unilaterally build the wall and is making a campaign-style pit stop in El Paso, Texas, on Monday.

"We have very, very strong legal standing to win," Trump said last week. "We are doing it regardless. I mean, we don’t have — we haven’t declared the national emergency yet, and yet we’re building a lot of wall."

"We’re continuing to build a lot of wall with, as we would say in business, 'cash on hand.'" he added. "And we’re negotiating tough prices. We have a great system. A great wall system. It's very uniform. They used to have all these different systems; nobody knew what was going on. We have a very good, solid system that looks good and is very powerful, as a wall."