Marjorie Taylor Greene, an influential far-right Republican in Congress, has called for the US to stop aid to Ukraine, giving added voice to a grassroots revolt in the party that threatens bipartisan support for the war against Russia’s Vladimir Putin.

The Georgia congresswoman is a notorious provocateur who has made racist, antisemitic and Islamophobic statements and promoted bizarre conspiracy theories.

Yet she has emerged as a prominent voice in the House of Representatives after forging a bond with the speaker, Kevin McCarthy, who vowed that Republicans will not write a “blank cheque” for Ukraine.

Greene told the Guardian that Joe Biden is “putting the entire world at risk of world war three”, a view widely held at the Conservative Political Action Conference (CPAC), America’s biggest annual gathering of conservatives.

“I think the US should be pushing for peace in Ukraine instead of funding and continuing a war that seems to be escalating and putting the entire world at risk of world war three,” Greene said during CPAC at the National Harbor in Maryland on Friday.

Greene called for US funding to cease immediately, insisting that, while she voted for a resolution to support the Ukrainian people and condemning Russia’s invasion, “we are actually accelerating a war there”.

She added: “We should be promoting peace. Europe should have peace and the United States should do their part. Ukraine is not a Nato member nation and Joe Biden said in the beginning he would not defend Ukraine because they’re not a Nato member nation. It doesn’t make sense and the American people do not support it.”

A year after Russia’s unprovoked invasion, the US has provided four rounds of aid to Ukraine, totaling about $113bn, with some of the money going toward replenishment of US military equipment that was sent to the frontlines.

The two leading contenders for the Republican presidential nomination in 2024, former president Donald Trump and the Florida governor, Ron DeSantis, have both expressed scepticism about the Ukraine cause. Opinion polls also show an erosion of public support.

The conflict was mostly absent from speeches on the main stage at CPAC, once the home of cold warrior Ronald Reagan but now a stronghold for the isolationist “America first” wing of the Republican party. Nikki Haley, a former ambassador to the UN who is running for president, and Mike Pompeo, an ex-secretary of state weighing his own run, gave the subject a wide berth in their addresses.

But outside the cavernous ballroom with its glitzy red, white and blue stage, neat rows of seats and banks of TV cameras, there was less circumspection and more crowd congestion. The rightwing podcaster and former White House strategist Steve Bannon repeatedly railed against the war in Ukraine before a noisy gathering of fans.

On Friday he was joined by Matt Gaetz, a Florida congressman who recently put forward a “Ukraine Fatigue” resolution in the House. Gaetz warned of the dangers of Russia’s nuclear arsenal and the threat of a third world war and said: “Zelinskiy’s new zeal for anti-corruption efforts and oversight seems to directly align with Republicans taking over the House of Representatives.”

Bannon rejoined: “Every Republican who supports this murderous war in Ukraine should be turfed out.”

Interviews with more than a dozen CPAC attendees elicited similar views and, in some cases, sympathy for Putin. Theresa McManus, wearing a cowboy hat and jacket, and a riding skirt patterned with words from the US constitution, said forcefully: “I like Putin. I think he’s got balls and he’s taking care of his country.”

Repeating a Kremlin talking point that people in the Donbas region want to be liberated from Ukraine, the 67-year-old horse trainer from rural Virginia continued: “No, we shouldn’t give them any more money. No, we should not be involved with them. They should not be part of Nato.”

Paul Brintley, 50, ambassador for the North Carolina Faith & Freedom Coalition, described Putin as “not so much a dictator” and said of Ukraine: “I don’t think we should be the police of the world. I don’t think we should bankroll them. We’ve done enough.”

Some at CPAC hew to conspiracy theories about the war. Jason Jisa, 41, from Dallas, Texas, said: “Show me where you’re sending the money. Show me war footage. Go look at all the previous wars: Afghanistan, Iraq, we’re flooded. We’re shown video of it every single day. You don’t see hardly any video come from Ukraine. Why? Where are the camera crews?”

Jisa, owner of the “USA Trump Store”, added: “Where’s the money going? Why are we on the hook for them? Why, while we have veterans in the street, we have homeless people all over the place, we have inflation going crazy, are we going to send billions and billions and billions of dollars?”

Ukraine is emerging as a wedge issue in the looming Republican primary election. Trump, who launched his campaign last November, has repeatedly called for an end to hostilities and claimed that, if he were to return to the Oval Office, he could end the war “within 24 hours”.

DeSantis, another potential contender, was viewed as a foreign policy hawk who embraced tough rhetoric against Putin while he served in Congress. But he has increasingly adopted a similar tone as he courts Trump’s populist base, though he did not attend CPAC.

But former vice-president Mike Pence, widely expected to launch a bid for the White House in the coming months, has called for Washington to intensify support for Ukraine and insisted that “there can be no room in the leadership of the Republican Party for apologists for Putin”. This stance is shared by the Senate minority leader, Mitch McConnell, and others in the party establishment.

Neither Pence nor McConnell came to CPAC, which some critics argue is losing relevance as it fails to shake off Trump. Hylton Phillips-Page, 67, a retired investment manager from Rehoboth Beach, Delaware, described Putin as a “thug” but admitted “mixed feelings” over continued aid for Ukraine.

“I don’t think our support can forever be at the expense of our own country. I would be quite OK with our Congress saying: until you finish the wall and protect our own border, you shouldn’t be protecting somebody else’s border. I’m not opposed to supporting them but I would like us to do some stuff at home.”

Antwon Williams, 40, from Columbia, South Carolina, who was selling Trump merchandise, said: “America needs to worry about the troops that we have, our veterans that need our help here in America, instead of writing an unlimited cheque to these people out here,” he said.

“No offence to them [Ukrainians]. It’s horrible what they’re going through. No one wants to see anyone hurting and dying out there. But we have our own veterans that fought for America and our freedom that is hurting, that is homeless, that is needing help, who have mental issues and who are starving right here in America.”