A bipartisan coalition of senators on Monday night pushed a $95 billion foreign aid package for Ukraine and Israel to the brink of passage, as Republicans fractured bitterly over the bill, with opponents threatening to fight it until the very end.

On a vote of 66 to 33, the measure cleared its last hurdle before a final vote, with 17 Republicans joining almost all Democrats to help advance it over the full-throated objections of the bulk of G.O.P. senators, Republican leaders in the House and the party’s likely presidential nominee, Donald J. Trump. That put the bill on track to pass the Senate no later than Wednesday.

But the measure’s fate was uncertain as Republican foes of the legislation promised to delay Senate passage as long as possible, and as Speaker Mike Johnson suggested he had no intention of bringing it up in the House, where the majority of Republicans have opposed continuing to send aid to Ukraine.

“House Republicans were crystal clear from the very beginning of discussions that any so-called national security supplemental legislation must recognize that national security begins at our own border,” Mr. Johnson said in a statement, adding: “In the absence of having received any single border policy change from the Senate, the House will have to continue to work its own will on these important matters.”

Mr. Trump and his right-wing allies have been pressuring Senate Republicans relentlessly to abandon the legislation, which would provide $60.1 billion to help Ukraine fight off a Russian invasion, $14.1 billion for Israel’s war against Hamas and almost $10 billion toward humanitarian aid for civilians in conflict zones, including Palestinians in Gaza. The bulk of Republicans in Congress have repudiated the measure, reflecting a turn away from the party’s traditional hawkish stance and belief in projecting American power and democratic principles around the world.

Mr. Trump in particular has been railing against the legislation from the campaign trail. In recent days, he has cheered G.O.P. senators for killing an earlier version of the bill that included a bipartisan deal on border security, argued on social media that it was “stupid” for the United States to offer foreign aid instead of loans, and encouraged Russia to “do whatever the hell they want” to NATO members that did not spend enough money on their own defense.