The Senate adjourned Wednesday evening still in search of more Republicans who will vote for U.S. aid to Israel, Ukraine and Taiwan.
The chamber will hold a procedural vote Thursday on a $95 billion national security package with funds for the three countries.
Republicans on Wednesday blocked a separate bill that included the aid and a border-security deal, assailing the immigration portion as inadequate to curb the stream of illegal entries.
But the Senate remained two votes shy of the 60 that will be needed to advance the standalone aid, as Republicans search for any additional supporters.
“We will recess until tomorrow and give our Republican colleagues the night to figure themselves out,” said Senate Majority Leader Charles E. Schumer, New York Democrat.
At least eight Senate Republicans indicated they were prepared to help Democrats advance the foreign aid without the border deal, a remarkable reversal from prior GOP demands.
Sen. Bernard Sanders, a Vermont independent who caucuses with Democrats, indicated he will not vote for the aid unless restrictions are placed on military support for Israel over the high civilian death toll in its war against Hamas.
Senate Minority Leader Mitch McConnell of Kentucky was among the Republicans on board with the aid.
“If America fails to stand with our partners on the front lines in Europe and the Middle East, we will shred our credibility with friends in the Indo-Pacific,” Mr. McConnell said.
“Today’s strategic competition is more perilous. Support for our allies is more tenuous. And the security of U.S. personnel and interests is more questionable than it was three years ago,” he said.
The Senate is ultimately back where it was in the fall, before months-long border negotiations, only this time with Republican support for moving ahead without addressing the crisis at the U.S.-Mexico border.
Additional Republicans could emerge supportive of the standalone aid, if an agreement with Democrats is reached on amendment votes.
Some Republicans were seeking amendment votes on illegal immigration, despite hours earlier voting against the border deal.
Sen. James Lankford of Oklahoma, Republicans’ chief negotiator for the border provisions, borrowed a talking point from Democrats to accuse his GOP colleagues of playing election-year politics with a contentious policy.
He revealed that an unnamed “popular commentator” approached him weeks ago with a threat.
Mr. Lankford recalled the person saying: “If you try to move a bill that solves the border crisis during this presidential year, I will do whatever I can to destroy you because I do not want you to solve this during the presidential election.”
Mr. Lankford added: “They have been faithful to their promise and have done everything they can to destroy me in the past several weeks.”
The foreign aid bill would still need final approval, if advanced on Thursday. That could come as soon as later this week before the Senate embarks on a two-week recess.
But even if it clears the upper chamber, its prospects in the Republican-controlled House are dim.
House Republicans have previously rejected more aid to Ukraine unless stringent border security measures are attached.