The Senate voted 52-47 to approve the legislation, with no support from Democrats and no provision to ban a $US1.8 billion "anti-weaponisation" fund that could compensate President Donald Trump's political allies for allegations that the government mistreated them.
Senate Republican leader John Thune said the fund was a "settled issue", citing acting Attorney-General Todd Blanche's congressional testimony that the Department of Justice would not move forward with it, though Democrats say his word is insufficient.
Republicans have accused Democrats of "defunding" Immigration and Customs Enforcement and Border Patrol, despite the agencies having a combined $US100 billion in unspent funds that were part of a larger DHS spending package enacted in 2025 by Republicans, who control Congress.
Much of Thursday's long debate over the ICE funding bill was overshadowed by efforts from Democrats, and some Republicans, to insert language unrelated to immigration.
Those proposals revolved around prohibiting the use of federal funds and even private donations for building the lavish ballroom on White House grounds that Trump wants.
Senators also debated provisions making it illegal for federal dollars to be used for the anti-weaponisation fund.
None of those amendments were approved.
The funding provided by the bill would help pay for Trump's controversial migrant deportation crackdown over the next three years.
The bill goes to the House of Representatives for final passage.
Lawmakers began voting on amendments to the immigration bill early on Thursday that culminated in the vote on the underlying measure early on Friday.
An initial move by Senate Democratic leader Chuck Schumer to kill the "anti-weaponisation" fund, which Democrats call a slush fund for Trump's allies, brought the session to a largely procedural halt for hours after Republican senator Susan Collins voted for the motion.
She was later joined by fellow Republicans Jon Husted and Dan Sullivan.
Schumer's measure narrowly failed but exposed the political turmoil among rank-and-file Senate Republicans, five months before midterm elections.
Collins, Husted and Sullivan face competitive races for re-election at a time when Trump's approval rating is down, even among Republicans.
"Republicans refused to permanently outlaw Trump's $US2 billion slush fund, leaving taxpayers to rely on nothing more than a promise from Donald Trump's personal fixer," Schumer said in a statement after the final vote, referring to Blanche.
The fund has already been put on hold by the White House and Justice Department.
But on Wednesday, Trump declined to say whether it had actually been terminated, telling reporters: "I love it. I think it's so important."
