Vladimir Putin has proven adept at exploiting the US political divide, so the solid bipartisan consensus behind arming Ukraine over the past year may well have come as a surprise to him. The question one year into the war is: how long can that consensus last?

Two weeks before the first anniversary of the full-scale invasion on 24 February, a group of Trump-supporting Republicans led by Matt Gaetz introduced a “Ukraine fatigue” resolution that, if passed, would “express through the sense of the House of Representatives that the United States must end its military and financial aid to Ukraine, and urges all combatants to reach a peace agreement”.

The resolution is sponsored by 11 Republican members of Congress on the far right Freedom Caucus faction, and is highly unlikely to pass. But it marks a shot across the bows of the leadership, which has mostly vowed to stay the course in supporting Ukraine.

Justifying the resolution, Gaetz pointed to the risks of escalation of the Ukraine war into a wider global conflict and to the economic cost to the US.

“President Joe Biden must have forgotten his prediction from March 2022, suggesting that arming Ukraine with military equipment will escalate the conflict to ‘World War III’,” the Florida Republican said. “America is in a state of managed decline, and it will exacerbate if we continue to haemorrhage taxpayer dollars toward a foreign war.”

The influence of this faction is heightened by the fact that the Republicans have a slim nine-seat majority in the House, and the new speaker, Kevin McCarthy, only scraped into the job after 15 rounds of voting among Republican members, during which he gave promises to listen to the concerns of hard-right holdouts like Gaetz.

“I’ve been sounding the alarms on Republican opposition to Ukraine aid for the last 12 months,” the Democratic senator Chris Murphy said. “Right now, there are enough Republicans in the Senate who support Ukraine aid along with all of the Democrats, so we can continue to deliver support, but I don’t know what’s going to happen in the House.”

“I think there’s going to be tremendous pressure on Speaker McCarthy to abandon Ukraine … and it’s possible he could wilt under the pressure,” Murphy said. “We know the Russians see this as a real opportunity.”

European diplomats have been lobbying Republicans, underlining the importance of maintaining western solidarity in the face of Russian aggression and arguing that support for Ukraine is an extremely inexpensive way to degrade the military of a hostile power seen by the Pentagon as an “acute threat”.

The diplomats report reassuring noises from the party leadership, but unwavering resistance from the rightwingers, many of whom follow the lead of the Trump camp, particularly the former president’s son, Donald Trump Jr, who has railed against western backing for Ukraine, and ridiculed its president, Volodymyr Zelenskiy.

“The divide in the US is now more tangible than in Europe. The Republican leadership is absolutely adamant that there will be no lessening of support for Ukraine, but it’s just words,” one European diplomat said. “With such a narrow Republican majority in the House, the Freedom Caucus has a lot of influence. And you don’t need to cut off help overnight. You just need to slow it down with procedure. That’s the danger.”

Some of Washington’s European allies are less concerned. One noted how upbeat McCarthy was on the issue, and the commitment to Ukraine of the Republican leader in the Senate, Mitch McConnell.

Frank Luntz, a Republican political consultant, also argued the pro-Russian lobby in the party had been permanently diminished.

“Trump used to call Putin a genius. You don’t hear him saying that anymore,” Luntz said. “Most of these people have backed down because they realise they were completely wrong. Donald Trump blew it in Ukraine and there are people who hold it against him to this day.”

“You have a few dozen members who are hostile now and that will increase, and could even double. But I don’t expect our support for Ukraine to ebb,” he added.

However, a recent opinion poll has shown support softening for the continued arming of Ukraine as the war approached its one-year milestone. In the survey by the Associated Press and the National Opinion Research Center, 48% of those questioned said they were in favour of providing weapons, with 29% opposed. Last May, 60% of Americans surveyed supported arming Ukraine.

It is against that backdrop that Biden will fly to Poland on Monday to mark the approach of the anniversary and to restate the case for western solidarity with Ukraine.

Murphy predicted that the House speaker, who has himself warned that there would no longer be a “blank cheque” for Ukraine with a Republican majority, might seek a compromise with the right of the party that could eventually prove devastating.

“I worry that McCarthy will try to split the baby and support funding for hard military infrastructure but not support economic and humanitarian aid,” the Democratic senator said. “If that’s the direction that US funding goes, it’s a recipe for the slow death of Ukraine.”