The Republican meltdown on Capitol Hill that toppled the speaker this week and left the House in chaos has also highlighted a sharp decline in G.O.P. support for continuing to send aid to Ukraine, and how opposition to helping Kyiv has become a litmus test for the far right.
The intensifying shift is striking for a party that has long defined itself by its belief in a muscular American military defending democracy around the world. And it could make it far more difficult for the Biden administration to fulfill its promise to support Ukrainian fighters for the long haul.
Hard-line Republican critics have long espoused isolationist views about Ukraine’s war effort, arguing that sending tens of billions of dollars to Kyiv risks dragging the United States into a head-on conflict with Russia and siphons money away from domestic challenges. Former President Donald J. Trump popularized the argument with his “America First” approach to foreign policy, but until recently, most lawmakers refrained from embracing it.
But the drama that has played out in the House over the last week, as Republicans pushed the government to the brink of a shutdown and then deposed their own speaker, has made clear that the right-wing message is gaining momentum among Republicans.
In the past few days, Republicans managed to strip billions in military and humanitarian assistance requested by Mr. Biden out of a stopgap spending bill to keep the government from shutting down. They rallied a majority of their colleagues in the House to vote against funding a program to train and equip Ukrainian troops. And a small faction of hard-liners joined with Democrats to boot Representative Kevin McCarthy, Republican of California, as speaker after accusing him of making a “secret side deal” with Mr. Biden to fund Kyiv’s war against Russia.
The division among Republicans on the issue is now on vivid display in the fight to replace Mr. McCarthy, which pits Representative Steve Scalise of Louisiana, the No. 2 Republican who has backed aid to Ukraine, against Representative Jim Jordan of Ohio, the Judiciary Committee chairman who is vocally opposed.
While the naysayers still represent a minority overall in Congress, the dramatic shift in Republican sentiment has left Ukraine’s boosters in the party angry, alarmed and working to figure out how to reverse the trend before a lapse in funding hampers Ukraine on the battlefield.
They were particularly concerned last week, when 117 Republicans — a majority of their members — voted against a bill that would fund a $300 million program to train and equip Ukrainian fighters. The bill passed, but that level of G.O.P. opposition almost certainly spells trouble ahead in the House, where Republicans typically refuse to take action on anything that does not have the backing of a majority of their own members.
Representative Mike D. Rogers, Republican of Alabama and the chairman of the Armed Services Committee, lamented what he called a “small contingent” of rabble rousers “who have turned this into a bargaining chip for their schemes.”
They “have stirred up our base to make them think that if you’re for Ukrainian funding that you can’t be for a secure border, or you’re a lib or whatever,” Mr. Rogers added. “But when you talk with people, they don’t have a problem, they just don’t want to get in trouble back home.”
There were signs earlier this year that Ukraine aid might be in trouble. In June, Mr. McCarthy said he was against putting an emergency spending package for Ukraine to a vote on the House floor, citing a deal he had just struck with Mr. Biden to set federal spending limits in exchange for suspending the debt ceiling.
Then in July, the House voted on several amendments to block Congress from authorizing military assistance funds for Ukraine as part of its consideration of the defense authorization bill. All failed — but revealed that Ukraine skepticism in the Republican Party had grown by a couple dozen votes since the year before.
The trend accelerated noticeably after lawmakers went home for an extended summer recess to spend time with constituents. When they returned to Washington, dozens more were joining critics to vote against Ukraine funding. Politics and public pressure, apparently, had tipped the scales.
“This is a very unpopular issue — not with just Republican voters, but also with Americans,” said Representative Marjorie Taylor Greene, Republican of Georgia and one of the lawmakers leading the charge against Ukraine funding. Citing a recent CNN poll that found that a majority of Americans opposed continued financial support for Ukraine’s war effort, she said the assistance had become a toxic issue, even for those previously inclined to support it.
One such Republican, Representative John Curtis of Utah, had voted in favor of Ukraine aid on multiple occasions in the past. But last week, he joined the critics and voted against funding the training program. He said he had done so to extract answers from the Biden administration about the pathway to victory, accountability, and the relative amount of skin other NATO countries were putting into the game.
“I support Ukraine in their war. I support continued funding for their efforts, but these are basic questions any organization would ask in a transaction,” Mr. Curtis said in a statement. “To continue spending Utahns’ taxpayer dollars, Congress must receive assurances to these questions.”
Even some strong Republican backers of aid to Ukraine now say it is difficult to imagine mustering the votes for another infusion without major policy and spending concessions from Democrats. Senator Lindsey Graham, Republican of South Carolina and an outspoken booster, has said the Senate could produce a package for Kyiv of as much as $60 billion or $70 billion — far surpassing Mr. Biden’s request for $24 billion. But he said it would have to be paired with severe immigration restrictions.
Mr. Biden is expected to deliver a major address on Ukraine aid in the coming days, but that forum is not conducive to discussing sensitive matters such as weapons tracking. President Volodymyr Zelensky of Ukraine used his recent visit to Washington to appeal for continued aid, but Mr. McCarthy declined to host a briefing where he could have made his case to members of the House and directly addressed their concerns.
Republican-led efforts to counter the skepticism surrounding Ukraine aid also have done little to stem the tide. Senator Mitch McConnell, the minority leader, spent nearly every day the Senate was in session in September making public appeals for Congress to fund the president’s request for Ukraine aid, arguing that the additional billions were also vital for U.S. national security and the domestic economy.
But even in the Senate, where three-quarters of Republicans continue to support Ukraine assistance, his desire to prioritize that fight was undermined by other G.O.P. senators anxious about crossing the Republican-led House. In a closed-door meeting on Saturday with only hours left to go before a potential shutdown, they decided to turn against their own stopgap spending bill that included funding for Kyiv and instead accept one drafted by Mr. McCarthy that did not.
That punted the question of future aid to Ukraine and left some Republicans bemoaning how the issue has become a politicized bargaining chip.
“Without President Trump’s leadership — I use the term very loosely — in the Republican Party, we would not be seeing this sort of opposition,” said Senator Todd Young, Republican of Indiana. “It’s just very hard to compete with the carnival barking that is occurring among a very vocal and energetic minority within our party.”
Catie Edmondson and Luke Broadwater contributed reporting.
