The US Senate on Sunday unveiled a US$118 billion bipartisan border security bill that would also provide aid to Ukraine and Israel following months of negotiations, but the measure faces an uncertain future amid opposition from hardline Republicans.

Senate Majority Leader Chuck Schumer said he would take steps to hold an initial vote on the bill on Wednesday. If the bill were to become law, it would mark the most significant changes in US immigration and border security in decades.

Some progressive Democrats are angry the measure does nothing to provide a pathway to citizenship for the 11 million undocumented people who have lived in the US for many years, including "Dreamer" immigrants who were brought in as children.

Independent Senator Kyrsten Sinema told reporters the legislation would secure the US southern border, including by requiring the Department of Homeland Security to temporarily "shut down" the frontier to most migrants if there are an average of more than 5,000 crossing attempts per day over seven days.

House of Representatives Speaker Mike Johnson said the bill would be "dead on arrival" if it reaches the House.

"This bill is even worse than we expected, and won’t come close to ending the border catastrophe the President has created," Johnson, a Republican, said on X, formerly called Twitter.

In addition to US$20.23 billion for border security, the bill included US$60.06 billion to support Ukraine in its war with Russia, US$14.1 billion in security assistance for Israel, US$2.44 billion to US Central Command and the conflict in the Red Sea, and US$4.83 billion to support US partners in the Indo-Pacific, according to figures from Senator Patty Murray, who chairs the Senate's Appropriation Committee.

An additional US$10 billion would provide humanitarian assistance for civilians in conflict zones, including in Ukraine, Gaza and the West Bank. (Reuters)