"If it's not supported on both sides of the aisle, then we shouldn't do this," Senator James Lankford told Reuters, the day after the bill was unveiled following months of negotiations.
Prominent Republicans including Donald Trump -- the frontrunner for his party's presidential nomination -- and House Speaker Mike Johnson have loudly voiced opposition.
The bill includes $118 billion in new spending, including $60.06 billion to aid Ukraine as it fights off a Russian invasion, $14.1 billion for Israel in its war against Hamas and about $20 billion for new enforcement along the U.S.-Mexico border.
Democratic Senate Majority Leader Chuck Schumer has said the chamber will hold a first procedural vote Wednesday on the bill, which would give the government emergency powers to refuse entry to migrants crossing the border or to quickly expel those who had already entered the U.S.
Lankford, who negotiated the bill with Democratic Senator Chris Murphy and independent Senator Kyrsten Sinema, said he would support a plan to allow amendment votes on the bill in both the Senate and House.
"It's important for the bill, period. I've said from the beginning, if it's not supported on both sides of the aisle, then we shouldn't do this," Lankford said at the Capitol. "Both the Senate and House should work their wills. People should have some ownership. I definitely think there are areas that could improve in the bill ... Let's start the conversation."
If the bill were to become law, it would mark the most significant changes in U.S. immigration and border security in decades.
It also faces opposition from progressive Democrats who are angry the measure does nothing to provide a pathway to citizenship for the 11 million undocumented people who have lived in the U.S. for many years, including "Dreamer" immigrants who were brought in as children.
(Reporting by David Morgan; Editing by Scott Malone and Chizu Nomiyama)
By David Morgan
