As a growing number of Republicans oppose U.S. aid to Ukraine, the Senate's leaders are arguing in strong terms that the money is crucial to pushing back against Russian President Vladimir Putin and maintaining America's global standing.

In the Capitol for a rare weekend session, the Senate voted again to move forward with the assistance as Senate Majority Leader Chuck Schumer, D-N.Y., and Republican leader Mitch McConnell of Kentucky issued stark warnings about the consequences of abandoning longtime U.S. allies in Europe.

“Today it’s no exaggeration to say that the eyes of the world are on the United States Senate,” McConnell said. “Our allies and partners are hoping that the indispensable nation, the leader of the free world, has the resolve to continue.”

The 67-27 test vote Sunday on the $95.3 billion aid package for Ukraine, Israel and other countries comes as former President Donald Trump, the front-runner for the Republican presidential nomination, is trying to kill the assistance and has escalated his attacks on the NATO military alliance.

Trump said Saturday at a campaign rally in South Carolina that Russia should be able to do “whatever the hell they want” to NATO members who do not meet their defense spending targets. He recounted a story he has told before about an unidentified NATO member who confronted him over his threat not to help them.

While McConnell has made Ukraine a top issue, an increasing number of members in his GOP conference have followed Trump’s lead and are opposing the aid, which Senate leaders have been trying to pass for months.

Without mentioning Trump by name, McConnell said in his opening remarks Sunday that “American leadership matters, and it is in question.”

Schumer said that if America doesn’t assist Ukraine, “Putin is all too likely to succeed.”

“The only right answer to this threat is for the Senate to face it down unflinchingly by passing this bill as soon as we can," Schumer said before the vote.

The Senate is pushing through several procedural votes on the slimmed-down package after an attempt to pair it with legislation to stem migration at the U.S. border collapsed. Objections from Republicans adamantly opposed to the aid have delayed quick action, forcing the weekend votes as negotiations continue over potential amendments to the legislation.

Schumer has said he is open to amendments -– most of which would be likely to fail -– but he forced senators to stay in session through the weekend to try and speed up the process.

“I can't remember the last time the Senate was in session on Super Bowl Sunday,” Schumer said as he opened the session. “But as I've said all week long, we're going to keep working on this bill until the job is done.”

In a key vote last week, 17 Republican senators agreed to start debate on the bill and 31 voted against it, giving McConnell and other Republican supporters of the aid new hope that it could pass.

But even if the Senate does pass the package, its future is deeply uncertain in the House, where a large majority of GOP lawmakers are firmly allied with Trump.

Amid shortages on the battlefield, the package would provide $60 billion for Ukraine, mostly to purchase U.S.-made defense equipment, including munitions and air defense systems that authorities say it desperately needs as Russia batters the country. It includes $8 billion for the government in Kyiv and other assistance.

It would also provide $14 billion for Israel’s war with Hamas, $8 billion for Taiwan and partners in the Indo-Pacific to counter China, and $9.2 billion in humanitarian assistance for Gaza.