In Washington Visit, Zelensky Will Try to Shore Up Critical Support

President Volodymyr Zelensky of Ukraine plans to make his second wartime visit to Washington on Thursday, meeting with President Biden and congressional lawmakers as he tries to preserve his country’s most critical source of funding and weapons.

Mr. Biden will be looking to get a “battlefield perspective” on the war from Mr. Zelensky, said John F. Kirby, a White House spokesman. The Ukrainian president, who was in New York this week rallying support at the U.N. General Assembly, also plans to visit Capitol Hill and the Pentagon.

The visit comes at a crucial moment in the war, with Ukraine’s fight against Russian invaders heading into the harsh winter months.

But it also comes as polls have detected a growing weariness over the war among the American public, which is focused on problems at home, and as dozens of Republicans say they are opposed to Mr. Biden’s latest request for $24 billion for additional military and humanitarian aid for Ukraine.

House Speaker Kevin McCarthy, whose position is imperiled by an extreme-right faction of his party that opposes Ukraine aid, plans to have a private meeting with Mr. Zelensky, but will not convene a forum for him to address members on Thursday.

“Where is the accountability on the money we already spent?” Mr. McCarthy told reporters on Tuesday. “What is the plan for victory? I think that’s what the American public wants to know.”

Mr. Biden has made support for Ukraine a centerpiece of his foreign policy, arguing that it is vital to American national security. He has continued to provide aid using previously approved funds, and Defense Secretary Lloyd J. Austin III announced this week that American M1 Abrams tanks would be arriving in Ukraine soon.

Ukraine has been lobbying for the United States to supply a powerful weapon called the Army Tactical Missile System, known as ATACMS (pronounced like “attack ’ems”), which Mr. Kirby said was not off the table.

ATACMS, which can strike targets 190 miles away with a warhead containing about 375 pounds of explosives, could help Kyiv regain Crimea, a part of the country Russia seized in 2014. But the United States has expressed fears about escalation.

“We’re trying to avoid World War III,” Mr. Biden has said.

Speaking to reporters on Wednesday, Mr. Kirby defended the weaponry the United States already has provided to Ukraine.

“We’ve evolved the capabilities as the war has evolved, as the needs evolve, and that has had a significant impact on the Ukrainians’ ability to defend themselves and to advance in this counteroffensive,” he said.

“The progress that they are making, though not as far or as fast as they themselves have said they’d like to go, is not by accident. It’s absolutely due in great measure to their bravery and skill on the battlefield. But it is also due, in no small way, to the support that the United States has provided them.”

Mr. Zelensky will encounter a different political climate than he found during his visit to Washington last year, when he received a hero’s welcome and an invitation from Nancy Pelosi, then the House speaker, to give a prime-time address to a joint session of Congress.

During that visit, Mr. Zelensky emerged from the Oval Office with a vow from Mr. Biden that the United States would continue to support Ukraine “for as long as it takes.”

On Thursday, House lawmakers who want to hear directly from Mr. Zelensky will have to leave Capitol Hill. Members of the Congressional Ukraine Caucus and others are expected to meet with him at the National Archives on Thursday.

Senator Chuck Schumer, Democrat of New York and the majority leader, has organized a closed-door session in the Capitol for all 100 senators.

Mr. McCarthy has said he plans to press Mr. Zelensky on how Ukraine is spending the aid the United States has provided so far — earlier this year, Mr. McCarthy declined Mr. Zelensky’s invitation to visit Ukraine to see for himself — as a federal spending fight in Congress threatens to tie up the White House’s funding request and shut down the government.

Mr. Kirby said the White House was confident that it would continue to see strong support for Ukraine.

“There is no such thing as a blank check for Ukraine, because every single thing that we’re providing to Ukraine is done in full consultation with members of Congress,” he said.

As Mr. Biden tries to secure the new funding, the 2024 election is looming.

Former President Donald J. Trump, the front-runner to be the Republican nominee, could make the war a central issue in the campaign.

At a rally over the summer, he said Congress should refuse to send any more weapons until the F.B.I., I.R.S. and Justice Department “hand over every scrap of evidence they have on the Biden crime family’s corrupt business dealings.”

Polls also suggest support is softening among Americans. A recent CNN poll found that most Americans believed that Congress should not authorize more funding to support the war.

Karoun Demirjian contributed reporting.