WASHINGTON (NewsNation) — The fall of Mariupol appears at hand as Ukraine is moving to abandon a sprawling steel plant where its soldiers had held out under relentless bombardment for months, which would make it the biggest city to fall into Russian hands.

Meanwhile, negotiations are underway for a prisoner swap, although it’s not clear yet that one will be reached. This comes as billions of dollars in U.S. aid could soon be on the way following this major setback for Ukraine.

The Senate voted late Monday to advance the Ukraine aid bill 81-11, pushing it toward President Joe Biden’s desk by week’s end to become law. But more vocal objections from Republicans in Congress are sending warning signs after what has been rare and united support for Ukraine as it desperately battles hostile Russia. All 11 no votes came from Republican senators.

While a strong bipartisan majority is poised to approve the latest round of Ukraine aid, bringing the U.S. total to $53 billion since the start of Russia’s invasion, it’s clear that Republicans, and some Democrats, are wary of a prolonged intervention and demanding a more fulsome accounting of the U.S. role overseas. While the House overwhelmingly approved the $40 billion package last week, 57 Republicans voted against it.

It comes as Senate Republican Minority Leader Mitch McConnell finds himself holding down the GOP’s more traditional foreign policy approach in direct confrontation with the GOP’s “America First” flank, including Donald Trump, the former president.

“There’s always been isolationist voices in the Republican Party,” McConnell told reporters on a conference call over the weekend from Stockholm. “It won’t create a problem, we’ll get the job done.”

The 11 Republican senators have consistently voted against advancing the aid package; some say the money should be spent in the U.S. to defend the southern border.

The most vocal lawmakers are insisting Congress will not become a blank check for overseas action amid domestic needs as they move away from the U.S.’s longstanding role of championing democracy abroad.

“We have got to take care of things here at home first,” said Republican Sen. Bill Hagerty of Tennessee, the former Trump administration’s ambassador to Japan, on Fox’s “Sunday Morning Futures.”

Republican Sen. Josh Hawley of Missouri tweeted about his no vote: “That’s not isolationism. That’s nationalism.”

McConnell told reporters on a call after visiting President Volodymyr Zelensky in Ukraine over the weekend that this isn’t an either/or situation, and this would not be a handout or charity for Ukraine, but that this aid package is intended to help prevent a “ruthless thug” from beginning a march through Europe.

That debate is playing out in the Senate, amid the last Ukrainian defenders in Mariupol are surrendering, ending one of the longest battles since the Russian invasion started on Feb. 24.

Ukrainian President Volodymyr Zelenskyy said Ukraine is working on getting its remaining troops safely out of the Azovstal steel plant.

In his nightly video address to the nation, Zelenskyy said the evacuation mission was supervised by Ukraine’s military and intelligence officers, and “the most influential international mediators are involved.”

However, hundreds of Ukrainian fighters have left the Azovstal steel plant and turned themselves over to Russian hands.

Ukrainian military officials hope they can be exchanged for Russian prisoners of war. The Russian Defense Ministry estimates at least 1,000 Ukrainian troops have surrendered from the Azovstal steel plant since Monday.