A sweeping US foreign aid package, including $60 billion for Ukraine, passed a key procedural vote Sunday, although opposition from right-wing Republicans may block it from becoming law.
The $95 billion package includes funding for Israel's fight against Hamas militants and for key strategic ally Taiwan, but the lion's share would help pro-Western Ukraine restock depleted ammunition supplies, weapons and other crucial needs as it enters a third year of war.
The Senate, which has a very slim Democratic majority, voted 67-27 to break a procedural hold placed on the bill, making it almost certain it will pass a final simple-majority vote around midweek.
It is unusual for the Senate to hold votes on the weekend, with Sunday's session also coinciding with the all-important NFL championship game.
"I can't remember the last time the Senate was in session on Super Bowl Sunday, but as I've said all week long, we're going to keep working on this bill until the job is done," Senate Majority Leader Chuck Schumer said before the vote.
"As we speak, Vladimir Putin's invasion of Ukraine has rendered parts of Eastern Europe a war zone the likes of which we have not seen in those regions since the Second World War," the New York senator said.
"The only right answer to this threat is for the Senate to face it down unflinchingly, by passing this bill as soon as we can."
The aid had looked dead in the water after Republicans rejected an earlier version on Wednesday that also attached to it many of the US-Mexico border security measures they had spent months championing.
Under pressure from ex-president Donald Trump, who is running for office again and wants to exploit Joe Biden's perceived weakness on immigration, Republicans instead appeared to decide that they would prefer stopping any border reforms until after November's election.
But Republican senators relented in a dramatic vote Thursday after the Democrats decoupled the Ukraine aid from the border issue entirely.
The two parties have been able to agree on little ahead of the elections. However, much of the dysfunction has been blamed directly on Trump, who looks almost certain to be the Republican standard-bearer in November despite losing the presidency to Biden in 2020 and being embroiled in multiple criminal charges.
Senate Republicans originally demanded border security as a condition for supporting pro-Western Ukraine as it battles the invasion launched by Putin in February 2022.
But Trump accuses Biden of failing to resolve the border issue, and has been loudly skeptical of Ukraine aid.
The hard-fought bipartisan compromise -- combining Ukraine and Israel funding with some of the toughest immigration curbs in decades -- was initially celebrated as a breakthrough on some of the most consequential issues facing the country.
However, the plan collapsed within days of its weekend release, as Trump warned lawmakers to reject it.
Then in a campaign speech Saturday, he threatened to stop defending NATO countries that fall short of spending commitments, prompting Biden to slam his "appalling and dangerous" comments and warn that the Republican intends to give Putin "a greenlight for more war and violence."
Even if the foreign aid advances from the Senate, it would still have to pass through the much more Trump-friendly House of Representatives.
Republican House Speaker Mike Johnson has not revealed whether he would be willing even to put a foreign aid-only bill on the floor for a vote.
Ukraine's President Volodymyr Zelensky posted on X, formerly Twitter, that the vote was a "very important first step" in freeing up more aid for his country, and a "bad day" for the Russian president.
