WASHINGTON ― Senate Democrats teed off on the GOP after Republicans walked away from bipartisan compromise legislation that they had said was urgently needed to secure the U.S. border, following pressure from former President Donald Trump.

“They are a disaster right now,” a visibly frustrated Sen. Chris Murphy (D-Conn.) told reporters Tuesday. “How can you trust any Republicans right now? They told us what to do. We followed their instructions to the letter. And then they pulled the rug out from under us in 24 hours.”

Murphy was the lead Democrat in charge of negotiating a set of bipartisan reforms to address the influx of migrants at the U.S.-Mexico border. Over the weekend, after four months of negotiations, Murphy released a bill alongside Sens. James Lankford (R-Okla.) and Kyrsten Sinema (I-Ariz.) that ran into a buzz saw of GOP opposition within minutes of it being made public. The backlash on the right was so fierce that Lankford himself has distanced himself from the bill.

On Tuesday, Senate GOP leaders drove the final nail in the coffin, suggesting that the Senate now move to pass a stand-alone U.S. foreign aid bill without the border provisions ― even though they were the ones who insisted on them in the first place.

For Murphy — who spent months in agonizing negotiations trying to achieve the impossible, a long-sought deal on immigration — the outcome couldn’t have been more frustrating.

“It’s 100 percent clear what’s happening here. The truth is simple. In the end, they sided with Donald Trump, who wants chaos at the border because it helps him politically,” Murphy said, adding that he was “disgusted” that Republicans asked Lankford to negotiate a compromise on their behalf and then knifed him in the back.

“I know that it’s easy to lose your sense of outrage … but what has happened here over the last four months is outrageous,” he added.

Deploying one of the biggest Senate put-downs, Murphy compared his colleagues in Congress’ upper chamber to those in the House, where cynicism and stunts are at a high.

“There used to be a difference between the Senate Republican caucus and the House Republican caucus,” Murphy said. “There is no difference. They are just as dysfunctional. They are just as tied to President Trump.”

Senate Majority Leader Chuck Schumer (D-N.Y.) was equally critical, saying that Republicans’ warnings about a crisis on the border ring hollow when they now maintain that it can wait until a Republican is in the White House again.

“Suddenly this crisis is not urgent. Suddenly we need even more time. … Give me a break,” Schumer said. “Today this is the new Republican line: It’s an emergency, but it can wait 12 months ― or till the end of time.”

He added, “They don’t have the backbone, the guts, the spine to resist the blandishments of Trump even when they know he’s wrong.”

Trump and his allies railed against the bill as a “betrayal” before it had even been unveiled, poisoning the well of potential support among the GOP base despite influential conservative voices endorsing the deal, including The Wall Street Journal’s editorial board and the union representing Border Patrol agents.

“It was my side that wanted to tackle the border. We started it,” Senate Minority Leader Mitch McConnell (R-Ky.) acknowledged to reporters Tuesday. “But as I said earlier, things have changed in the last four months, and it’s been made perfectly clear by the [House] speaker that he wouldn’t take it up even if we sent it to him.”

Sen. Thom Tillis (R-N.C.), who had supported bipartisan border talks and urged his GOP colleagues last month to show “courage” in bucking Trump, said that the “substance of the bill did not rise to the level that members felt they were comfortable to defend the policy.”

“I think it was just people in their heart of hearts saying, I’ve got to go home and sell this back home and it doesn’t fit the threshold for me to do that,” he added.

Top Senate Republicans are now advocating for the passage of a stand-alone bill that just includes aid to Ukraine, Israel and Taiwan ― which is exactly what President Joe Biden’s administration proposed in October before House Speaker Mike Johnson (R-La.) demanded the border policy changes. That would essentially mean going back to square one, with months of wasted time on negotiations.

But there are now doubts on whether even that bill could pass in the Senate and receive a vote in the House, where many Republicans are opposed to the idea of helping Ukraine survive amid the invasion by Russia.

For now, Senate Republicans are hoping that Johnson can figure out what they couldn’t.

“Somebody has to be an adult in the room,” Sen. Kevin Cramer (R-N.D.) said on Tuesday about that scenario.