A sweeping foreign aid package easily passed the U.S. Congress late Tuesday after months of delay, clearing the way for fresh Ukraine funding amid advances from Russia's invasion force and Kyiv's shortages of military supplies.

The U.S. Senate voted 79 to 18 to approve four bills passed by the House of Representatives on Saturday, after House Republican leaders abruptly switched course last week and allowed a vote on the $95 billion US in mostly military aid for Ukraine, Israel and Taiwan, and U.S. partners in the Indo-Pacific.

The four bills were combined into one package in the Senate, which U.S. President Joe Biden said he would sign into law on Wednesday.

The largest provides $61 billion US in critically needed funding for Ukraine; a second provides $26 billion US for Israel and humanitarian aid for civilians in conflict zones around the world; and a third mandates $8.12 billion US "to counter communist China" in the Indo-Pacific.

A fourth, which the House added to the package last week, includes a potential ban on the Chinese-controlled social media app TikTok, measures for the transfer of seized Russian assets to Ukraine, and new sanctions on Iran.

Biden's administration is already preparing a $1-billion US military aid package for Ukraine, the first to be sourced from the bill, two U.S. officials told Reuters. It includes vehicles, Stinger air defence munitions, additional ammunition for high-mobility artillery rocket systems, 155-millimetre artillery ammunition, TOW and Javelin anti-tank munitions and other weapons that can immediately be put to use on the battlefield.

The Senate's Democratic and Republican leaders predicted that Congress had turned the corner in putting Russian President Vladimir Putin and other foreign adversaries on notice that Washington will continue supporting Ukraine and other foreign partners.

"This national security bill is one of the most important measures Congress has passed in a very long time to protect American security and the security of Western democracy," Democratic Majority Leader Chuck Schumer told a news conference after the vote.

The aid package could be the last approved for Ukraine until after elections in November, when the White House, House of Representatives and one-third of the Senate are up for grabs.

Much of the opposition to the security assistance in both the House and Senate has come from Republicans with close ties to former U.S. president Donald Trump, a Ukraine aid skeptic who has stressed "America First" policies as he seeks a second term in November.

Senate Republican Leader Mitch McConnell, a strong advocate for assisting Ukraine, expressed regret about the delay, largely due to hardline Republicans' objections to adding more to the $113 billion US Washington had authorized for Kyiv since Russia began its full-scale invasion in February 2022.

"I think we've turned the corner on the isolationist movement," McConnell told a news conference.

Ohio Sen. J.D. Vance, a Republican who is a close ally to Trump, said that despite the strong showing of support for funding Ukraine's defence, opposition is growing among Republicans.

"The United States is spread too thin," Vance said.

"That argument, I think, is winning the American people and it's slowly winning the Senate, but it's not going to happen overnight."

Some of the Ukraine money — $10 billion US in economic support — comes in the form of a loan, which Trump had suggested. But the bill lets the president forgive the loan starting in 2026.

The influx of weapons should improve Kyiv's chances of averting a major Russian breakthrough in the east, analysts said, although it would have been more helpful if the aid had come closer to when Biden requested it last year.

Schumer said he left a message for Ukrainian President Volodymyr Zelenskyy on Tuesday night, telling him, "OK, we got it done. Now go win the fight."

The legislation's progress has been closely watched by industry, with U.S. defence firms up for major contracts to supply equipment for Ukraine and other U.S. partners.

Experts expect the supplemental spending to boost the order backlog of RTX Corp along with other major companies that receive government contracts, such as Lockheed Martin, General Dynamics and Northrop Grumman.