WASHINGTON — Congressional negotiators said Monday night they had reached an "agreement in principle" to prevent another partial government shutdown that would further fund border security but would include no money for President Donald Trump's border wall.

The deal would match 2018's funding level for what officials described as new border fencing that could include steel slats and other "existing technologies" but would not be a concrete wall. It would also provide an additional $1.7 billion for other Homeland Security priorities like new technology and more customs officers, multiple sources told NBC News.

Senate and House negotiators from both parties who emerged from an evening meeting would not comment on the details of the deal because they said staff was still working on last-minute logistics.

"We reached an agreement in principle," Senate Appropriations Committee Chairman Richard Shelby, R-Ala., told reporters. "Our staffs are going to be working feverishly to be putting all the details together, and that’s all we can tell you now."

The agreement came in a third round of talks on Capitol Hill following a weekend of stalled negotiations, and just ahead of a "Make America Great Again" rally that Trump was held in El Paso, Texas, on Monday night.

The White House didn't comment on the agreement and Trump said at the rally, "We probably have some good news but who knows."

The details of the deal, according to multiple sources, were as follows:

$1.375 billion for border barrier enhancements like steel slats and other "existing technologies," but no concrete wall

The money would fund about 55 miles of new barrier

Geographic restrictions on where the new fencing could built, likely limited to the Rio Grand Valley sector of the border

DHS would receive $1.7 billion in new funding for border security that could include technology at ports of entry, additional customs officers and humanitarian aid

No cap on the number of beds for enforcing immigration laws in the country's interior

Funding for approximately 40,520 detention beds for detained immigrants

Top Democratic negotiators Rep. Nita Lowey of New York and Sen. Patrick Leahy of Vermont met behind closed doors with their Republican counterparts, Rep. Kay Granger of Texas and Shelby.

Over the weekend, a new sticking point had emerged in the negotiations: not the border wall, but the number of detention beds for undocumented immigrants who enter the country.

A senior Democratic aide told NBC News on Sunday that Senate Republicans would need to accept "limits" on Trump immigration policies in the form of a cap on the bed count.

Democrats appeared to have backed off of the demand during the negotiations, and speaking at his rally in El Paso Monday night, Trump said, "I will never sign a bill that forces the mass release of violent criminals into our country."

“These are people, they kidnap people. These are people the Democrats want to come into our society. I don’t think so," the president told a group of sheriffs at the White House earlier Monday. "I don’t know, maybe we’re in a different country than I know of.”

Acting White House chief of staff Mick Mulvaney, who hosted several members of Congress at Camp David over the weekend, said on NBC’s “Meet the Press” on Sunday that the White House "absolutely cannot" rule out another government shutdown.

"Let's say the hard-core left wing of the Democrat Party prevails in this negotiation and they put a bill on the president's desk with, say, zero money for the wall, or $800 million, an absurdly low number. How does he sign that?" he said.

Republicans had started to discuss the idea of proposing a one-year continuing resolution that would keep funding at current levels, but it had not been clear that Democrats, who control the House, would accept that, or whether President Trump would sign it.

Trump tweeted Sunday that negotiations were going poorly. “The Border Committee Democrats are behaving, all of a sudden, irrationally. Not only are they unwilling to give dollars for the obviously needed Wall (they overrode recommendations of Border Patrol experts), but they don’t even want to take muderers [sic] into custody! What’s going on?”