Washington signalled room for negotiation on a US plan to end the Ukraine war that has drawn pushback from Kyiv, its allies and US lawmakers ahead of Sunday talks on the proposal in Switzerland.

Trump has given Ukraine until November 27 to approve the plan to end the nearly four-year conflict, but Kyiv is seeking changes to a draft that accepts some of Russia's hardline demands.

Washington insisted Saturday the proposal was official US policy, denying claims by a group of US senators that Secretary of State Marco Rubio told them the document was a Russian"wish list".

Trump's special envoy for Ukraine, Keith Kellogg, speaking on Fox News, described the plan as"a work in progress".

Ukraine's European allies, who were not included in drafting the proposal, said the plan requires"additional work" as they scrambled at the G20 summit in South Africa to come up with a counter-offer to strengthen Kyiv's position.

A US official told AFP that Rubio and diplomatic envoy Steve Witkoff would land in Geneva on Sunday for the talks and that US Army Secretary Daniel Driscoll had already arrived after meeting Ukrainian President Volodymyr Zelensky in Kyiv.

The dispute over the 28-point plan - which cedes Ukrainian territory long sought by Moscow - threw an extraordinary element of confusion into efforts to negotiate an end to the war.

US President Donald Trump has pushed the plan, pressuring the Ukrainians to accept it within days. However, after a storm of criticism that the proposal is almost entirely favorable to Moscow, several US senators spoke out, holding a press conference at the Halifax International Security Forum in Nova Scotia, Canada on Saturday.

The senators - Republican Mike Rounds, independent Angus King, and Democrat Jeanne Shaheen - said Rubio told them the current Ukraine proposal is not the official US position, but instead lays out a"Russian wish list."

"What he (Rubio) told us was that this was not the American proposal. This was a proposal that was received by someone... representing Russia in this proposal. It was given to Mr Witkoff," Rounds said, referring to Trump's diplomatic envoy Steve Witkoff.

"It is not our recommendation. It is not our peace plan."

King corroborated those comments, saying"the leaked 28-point plan - which according to Secretary Rubio is not the administration's position - it is essentially the wish list of the Russians that is now being presented to the Europeans and to the Ukrainians."

The plan would require Kyiv to cede territory, cut its military, and pledge never to join NATO.

Trump said Saturday it was not his final offer and he hoped to stop the fighting"one way or the other."

'Authored by the US'

Rubio asserted the proposal "was authored by the US."

"It is offered as a strong framework for ongoing negotiations. It is based on input from the Russian side. But it is also based on previous and ongoing input from Ukraine," he said Saturday.

But Shaheen said she and Rounds spoke to the top US diplomat while he was en route to Geneva for the latest negotiations with Ukrainian officials.

Rounds said Rubio was"very frank" during their call.

"It doesn't look like normally something that would come out of our government, particularly the way it was written. It looked more like it was written in Russian to begin with," Rounds said.

King noted that the plan should not reward Moscow for its invasion.

"Everyone wants this war to end but we want it to end on a fair and just peace that respects the integrity and the sovereignty of Ukraine and does not reward aggression and also provides adequate security guarantees," he said.

Earlier Saturday, other US senators including some in Trump's Republican party criticized Washington's plan.

"We will not achieve that lasting peace by offering (Russian President Vladimir) Putin concession after concession and fatally degrading Ukraine's ability to defend itself," the group of senators wrote in a statement.

Senator Mitch McConnell, a veteran Republican, said"rewarding Russian butchery would be disastrous to America's interests."

Russian 'representatives' expected

Zelensky has issued a decree naming Ukraine's delegation for the talks, led by his top aide Andriy Yermak. It also says the negotiations would include"representatives of the Russian Federation" but there was no immediate confirmation from Moscow whether it would join the talks.

Zelensky said"consultations will take place with partners regarding the steps needed to end the war"."Our representatives know how to defend Ukraine's national interests and what is necessary to prevent Russia from launching a third invasion," having annexed Crimea in 2014 and mounted a full-scale offensive in 2022, he said.

Britain's Prime Minister Keir Starmer said the senior officials would meet in Geneva"to take things further forward", stressing the importance of solid"security guarantees" for Ukraine under any settlement.

"The focus very much now is on Geneva tomorrow and whether we can make progress," he told reporters on the sidelines of the G20 summit in Johannesburg.

Starmer said his national security adviser, Jonathan Powell, would be in Geneva. Italian diplomatic sources said Rome was sending national security advisor Fabrizio Saggio.

Security officials from the EU, France and Germany will also attend, French President Emmanuel Macron told a news conference at the G20.

West says plan needs more 'work'

Western leaders at the G20 summit said that the US plan was"a basis which will require additional work".

"We are clear on the principle that borders must not be changed by force. We are also concerned by the proposed limitations on Ukraine's armed forces, which would leave Ukraine vulnerable to future attack," the leaders of key European countries, Canada and Japan said in a joint statement.

Macron said the plan contained points that had to be more broadly discussed as they concerned European allies, such as Ukraine's NATO ties and Russian frozen assets held in the EU.

"We all want peace and we are agreed. We want the peace to be strong and lasting," he said, insisting a settlement must"take into account the security of all Europeans".

Watch moreUS-Russia framework to end Ukraine war: Plan for peace or capitulation?

Zelensky said in an address to the nation on Friday that Ukraine faces one of the most challenging moments in its history, adding that he would propose"alternatives" to Trump's plan.

"The pressure on Ukraine is one of the hardest. Ukraine may face a very difficult choice: either the loss of dignity or the risk of losing a key partner," Zelensky said, referring to a possible break with Washington.

Russian President Vladimir Putin said the blueprint could"lay the foundation" for a final peace settlement, but threatened more land seizures if Ukraine walked away from negotiations.

Writing on X, he said that Putin has"spent the entire year trying to play President Trump for a fool."

Since the Russian invasion began in 2022, Ukrainian President Volodymyr Zelensky has vowed to keep Kyiv's territory intact.

In a Friday address to the nation, Zelensky said Ukraine faces one of the most challenging moments in its history, adding that he would propose"alternatives" to Trump's proposal.