Washington DC - Senators cleared a first hurdle Thursday to a sweeping foreign aid package – including a $60 billion in military assistance for Ukraine – although opposition from right-wing allies of Republican presidential candidate Donald Trump means final passage remains far from guaranteed.

The procedural vote to at least consider the bill nevertheless marked a stunning about-face by Senate Republicans.

Until now, they had refused to renew funding for Ukraine's fight against Russian invasion if Democrats didn't also agree to stringent new curbs on arrivals of undocumented migrants across the US-Mexican border.

The $95 billion package set to be debated also includes funding for Israel's military campaign in Gaza and for Taiwan. The lion's share, however, would help pro-Western Ukraine restock depleted ammunition supplies, weapons, and other crucial needs as it enters a third year of war.

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The aid had looked dead in the water after Republicans rejected an earlier version on Wednesday that also featured many of the repressive border measures they had spent months championing.

Under pressure from Trump, who is running for a second term and wants to exploit President 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. Biden himself has boasted that the border policy changes in the package would be the "toughest" in many years.

But Republican senators relented in a dramatic vote Thursday after the Democrats, who have a slim majority in the upper chamber, decoupled the aid from the border issue entirely. The procedural vote, which could open the way for a full vote in the coming days, capped an extraordinary spate of chaos in a deeply polarized Congress.

The two parties are 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 criminal charges.

Senate Republicans originally demanded border measures as a condition for supporting Ukraine as it battles the invasion launched by President Vladimir Putin in February 2022.

But Trump is running for a return to the White House on a platform centered around accusing Biden of failing to resolve border issues.

A hard-fought bipartisan compromise – combining Ukraine and Israel aid with some of the toughest immigration curbs in decades – was initially celebrated by centrist Democrats as a breakthrough on some of the most consequential issues facing the country. Immigrants' rights advocates, however, have sounded the alarm over the proposal, which could lead to even more human rights abuses at the border.

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The plan collapsed within days of its weekend release, as Trump warned lawmakers to reject it.

The new foreign-aid-only bill could still fail, with Senate Republicans divided between traditional conservatives and Trump's allies, who are against any action on the border before November's election and also oppose Ukraine aid. 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. And heated negotiations are taking place with House Republicans seeking to impeach Homeland Security Secretary Alejandro Mayorkas, who has become the main target for right-wing attacks over the border crisis.

"After earning the title of least productive Congress since the Great Depression, the House Republican chaos conference is back this year racking up loss after loss," said Democratic National Committee rapid response director Alex Floyd.

"Instead of focusing on real solutions to secure the border that have support from border patrol agents and Americans on both sides of the aisle, House Republicans have spent this week backtracking on their words and undermining their own professed priorities in order to do the bidding of Donald Trump."