Volodymyr Zelenskyy’s dramatic visit to Washington was a moment for the White House to demonstrate to Russia’s Vladimir Putin that the United States would sustain its commitment to the war for, as President Joe Biden put it, “as long as it takes.”

It also provided the Ukrainian president, dressed in military green, the opportunity in the grand setting of the U.S. Capitol to thank Congress for the billions of dollars that are sustaining his country in the fight.

“As long as it takes” is powerful rhetoric, but it now collides with a formidable question: How much more patience will a narrowly divided Congress — and the American public — have for a war with no clear end that is battering the global economy?

On Wednesday night, Zelenskyy made his case. In an address before a joint meeting of Congress, he melded Ukraine’s struggle to maintain its sovereignty with America’s battle for freedom. He spoke of the battle for Bakhmut — where a fierce, monthslong battle in eastern Ukraine is underway — as his country’s Battle of Saratoga, a turning point in the American Revolutionary War.

Zelenskyy, who visited the frontlines of Bakhmut shortly before traveling to Washington, presented members of Congress with a Ukrainian flag signed by the troops. And while he expressed thanks for U.S. aid, he also told the lawmakers “your money is not charity.”

“It’s an investment in global security and democracy that we handle in the most responsible way,” Zelenskyy said.

The majority of Americans, polls show, continue to support aid for Ukraine as it has managed to repel a Russian military some U.S. government officials initially believed would quickly overwhelm Ukrainian forces.

But the outmanned Ukrainians, with the help of some $21.3 billion in American military assistance since the February invasion, have managed to rack up successes on the battlefield and exact heavy losses on Russian troops.

Zelenskyy, seated next to Biden in the Oval Office, with a fire crackling in the fireplace behind them, acknowledged that Ukraine was in its more favorable position because of bipartisan support from Congress.

“We control the situation because of your support,” said Zelenskyy, who presented Biden with a medal that had been awarded to the Ukrainian captain of a HIMARS battery, a rocket system provided by the U.S., that the officer wanted Biden to have.

Yet even as support for Ukraine was being hailed by both Democratic House Speaker Nancy Pelosi and Senate Republican leader Mitch McConnell as serving core American interests, bipartisan unity on Ukraine was starting to fray.

“I hope that we’ll continue to support Ukraine, but we got to explain what they’re doing all the time,” Sen. Rick Scott, R-Fla., said shortly before Zelenskyy landed in Washington on Wednesday afternoon. “I think you have to keep selling things like this to the American public. I don’t think you can just say, you know, for the next, whatever time it takes.”

Just before Zelenskyy’s arrival, the U.S. announced a $1.85 billion military aid package for Ukraine, including Patriot surface-to-air missiles, and Congress planned to vote on a spending package that includes an additional $45 billion in emergency assistance to Ukraine.

Pelosi and others compared Zelenskyy’s visit to British Prime Minister Winston Churchill’s 1941 visit for talks with President Franklin D. Roosevelt following Japan’s bombing of Pearl Harbor.

Read more: Zelenskyy to meet Biden, address Congress as war rages on

Pelosi, in a letter to fellow lawmakers Wednesday, noted that her father, Rep. Thomas D’Alesandro Jr., was a House member when Churchill came to Congress on the day after Christmas “to enlist our nation’s support in the fight against tyranny in Europe.”

“Eighty-one years later this week, it is particularly poignant for me to be present when another heroic leader addresses the Congress in a time of war — and with Democracy itself on the line,” said Pelosi, who will soon step down as speaker with Republicans taking control of the House.

Biden, born less than a year after Churchill’s historic visit, observed that Zelenskyy has showed enormous fortitude through the conflict. “This guy has, to his very soul — is who he says he is. It’s clear who he is. He’s willing to give his life for his country,” Biden said during a news conference with Zelenskyy.

McConnell made the case in a speech on the Senate floor that supporting Ukraine is simply pragmatic.

“Continuing our support for Ukraine is morally right, but it is not only that. It is also a direct investment in cold, hard, American interests,” McConnell said.

Still, there are signs of discontent in the Republican conference.

Rep. Kevin McCarthy, who is vying to be the next House speaker when Republicans take over in the new year, as said his party won’t write a “blank check” for Ukraine once it’s in charge.

Some of the most right-leaning members of the Republican conference have lashed out at McConnell over his support of Ukraine.

Rep. Marjorie Taylor Greene, R-Ga., in a Wednesday morning Twitter post accused McConnell of pressing for passage of the $1.7 trillion spending bill that includes new funding for Ukraine “so that he can hand a $47 BILLION dollar check to Zelenskyy when he shows up in DC today.”

“But in my district, many families & seniors can’t afford food & many businesses are struggling bc of Biden policies,” she added.

For now, hers is mostly an isolated voice.

Unlike in other conflicts of the past half century in which the U.S. has been deeply involved — Vietnam, Iraq and Afghanistan — the cost of helping Ukraine has been strictly financial.

While the far right is beginning to turn up the volume on its skepticism on spending, the Ukrainian cause is an easier sell than those long costly conflicts, said Elliot Abrams, who served in senior national security and foreign policy roles in the Donald Trump, George W. Bush and Reagan administrations.

“With Ukraine, I think it’s much easier to make the argument that helping Kyiv resist Russian aggression is a valuable thing to do, and grinding down the Russian military is a valuable thing to do,” said Abrams, who is now chairman of the conservative foreign policy group Vandenberg Coalition. “And the cost of American lives is zero.”

As the war in Ukraine has passed 300 days, polling shows Americans have grown less concerned and less supportive of U.S. aid. In September, just 18% of U.S. adults said the U.S. wasn’t providing enough support to Ukraine, according to Pew Research Center, compared with 31% in May and 42% in March.

Still, about as many — 20% — said in September that the U.S. was providing too much support. About a third said the level of support was about right, and about a quarter weren’t sure.

Republicans were roughly three times as likely as Democrats to say support was too much, 32% vs. 11%.

Read more: G20: Zelenskyy, Biden trying to persuade world leaders to further isolate Russia

Biden acknowledged that the past 10 months have been difficult and lamented that Russian President Vladimir Putin showed no sign of having the “dignity” to call off the invasion. He assured Zelenskyy that the U.S. wasn’t going anywhere.

“You don’t have to worry, we are staying with Ukraine,” Biden said.

Petr Pudil, a board member of Slovakian-based nongovernmental group Globsec, said Zelenskyy’s mission of keeping America engaged is a difficult one, but he is up to the task. Pudil’s group earlier this month helped organize a visit to Washington by Ukrainian parliament members who made their case that American support is going to be needed for some time while assuring lawmakers that it will not be wasted.

“One of the goals of Zelenskyy for this trip is convincing those who are still skeptical that winning is a real option,” Pudil said. “But it can be done, and only if they deliver the right support. Everyone needs to understand that there is a chance to win.”