WASHINGTON (AP) — Signs of Republican resistance are mounting over a $40 billion aid package to Ukraine, a reemergence of the Trump-led isolationist wing of the GOP that's coming at a crucial moment as the war against the Russian invasion deepens.

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.

It comes as Senate Republican leader Mitch McConnell led a delegation of GOP senators to visit the region over the weekend in a show of support, vowing to push past detractors, finish up the aid package and vote this summer on expanding NATO to welcome Sweden and Finland. The leader 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 shift in Congress opens a new political phase in Ukraine's fight for its survival against the Russian invasion, offering a wake-up call for the Biden administration about its strategy as it resists direct U.S. military troop involvement and depends on votes in the House and Senate to fund the military and humanitarian relief effort.

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.

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 of his no vote: "That's not isolationism. That's nationalism."

It's stronger pushback than just a few months ago, at the start of war in February, when Congress made a rare show of bipartisan unity against Russian President Vladimir Putin's invasion and rushed to Ukraine's aid.

And it comes as the midterm election season is underway in the U.S., with Trump's influence looming large, particularly with Republican lawmakers desperate for his campaign endorsements and support and afraid to go against him.

"We have a moral obligation to pass this aid as soon as we can," Senate Majority Leader Chuck Schumer, D-N.Y., said Monday ahead of the procedural vote.

Trump weighed in, breaking the civic norm in the U.S. that former presidents traditionally step aside to allow one president at a time to lead, particularly on foreign policy.

The former president, whose "America First" strategy sought to pull back from U.S. commitments around the world and criticized the NATO military alliance confronting Russia, complained that Democrats are "sending another $40 billion to Ukraine, yet America's parents are struggling to even feed their children."

Trump had been impeached by the House in 2019 after he withheld military aid to Ukraine and pressured President Volodymyr Zelenskyy for a favor digging up dirt on Biden ahead of the U.S. presidential election, though he was later acquitted by the Senate.

On the campaign trail in Ohio, the U.S. Senate candidates, Democrat Tim Ryan and Trump-backed Republican JD Vance, have been brawling over the Ukraine assistance.

Vance, who quipped some months ago that he doesn't really care what happens in Ukraine, tweeted last week that Ryan "is pushing billions in foreign aid while the communities he serves in Congress have been decimated."

Ryan's team released an ad suggesting Vance as a venture capitalist had profited off a social media platform that is used to spread Russian propaganda.

The Senate was set to begin voting Monday evening on the $40 billion package, pushing past a Republican filibuster to advance the bill toward approval by Thursday.

The first round of Ukraine aid, $13.9 billion, was swiftly approved by Congress in March as part of a broader bill to fund the government. It came just before Zelenskyy delivered an address at a joint meeting of Congress to several standing ovations.

"Tonight, we are all Ukrainians," said Democratic Rep. Richard Neal of Massachusetts during the floor debate on the bill's passage.

But as months drag on, the lawmakers, particularly Republicans, are more assertive in their resistance, posing questions for the U.S. strategy ahead.

Republican Sen. Rand Paul of Kentucky single-handedly blocked a vote on the latest package last week as he demanded an inspector general's report on how the money is being spent.

The libertarian-leaning Paul routinely blocks spending bills with a filibuster, but he is also a non-interventionist when it comes to foreign policy who had great sway during the Trump era, encouraging the then-president's instincts against engaging in overseas actions.

"While I sympathize with the people of Ukraine, and commend their fight against Putin, we cannot continue to spend money we don't have," Paul said in a series of tweets about his blockade.

"It's frankly a slap in the face to millions of taxpayers who are struggling to buy gas, groceries, and find baby formula."

Outside groups influential with Republicans, including Heritage Action, have raised questions about the Ukraine spending. Fox News host Tucker Carlson said on his show last week he was calling every senators' office to see where they stood on the issue, putting pressure on the lawmakers.

McConnell a longtime advocate of the U.S. commitment to the NATO western military alliance and its broader role overseas, was the highest-ranking Republican to meet with Zelenskyy over the weekend in Kyiv.

McConnell said the Ukrainian president and people have been an inspiration as they fight the Russian invasion, and vowed the U.S.'s continued support and swift approval of Sweden and Finland's requests to join NATO before August.