The controversial 28-point proposal - which would hand swathes of land to Russia and limit the size of Kyiv's military - closely resembles the Kremlin's demands.
Mr Zelenskyy has warned he has reservations about the plan, telling Ukrainians in a solemn speech: "Now is one of the most difficult days in our history."
But Russian President Vladimir Putin has cautiously welcomed the US proposals - and said they "could form the basis for a final peace settlement".
Speaking to reporters at the White House, Mr Trump appeared to dismiss Mr Zelenskyy's concerns: "He'll have to like it... at some point, he's going to have to accept something."
The US president went on to reference their now-infamous Oval Office meeting back in February, where he told Ukraine's leader "you don't have the cards".
Kyiv has been given until Thursday to accept the peace plan - but this deadline could be extended to finalise the terms.
'I am highly sceptical it will achieve peace'
Mr Trump has received pushback from members of his own party, with a prominent Republican warning the plan "has real problems".
Senator Roger Wicker, who chairs the Senate Committee on Armed Services, expressed doubt that the White House proposals would achieve peace.
"Ukraine should not be forced to give up its lands to one of the world's most flagrant war criminals in Vladimir Putin," he warned.
Tim Ash from the Chatham House think tank added: "Russia gets everything it wants and Ukraine gets not very much.
"If Zelenskyy accepts this, I anticipate huge political, social and economic instability in Ukraine."
According to Reuters, European nations including the UK, France and Germany are now working on a counterproposal with Kyiv.
EU leaders, who were not consulted about the plan, will hold a meeting on the sidelines of the G20 summit in South Africa on Saturday.
Sir Keir Starmer, who spoke to Mr Zelenskyy by phone on Friday, has warned "Russia pretends to be serious about peace, but their actions never live up to their words".
Ahead of the talks, the prime minister said: "Ukraine has been ready to negotiate for months, while Russia has stalled and continued its murderous rampage. That is why we must all work together, with both the US and Ukraine, to secure a just and lasting peace once and for all. We will continue to coordinate closely with Washington and Kyiv to achieve that.
"However, we cannot simply wait for peace, we must strain every sinew to secure it. We must cut off Putin's finance flows by ending our reliance on Russian gas. It won't be easy, but it's the right thing to do."
The EU's foreign policy chief, Kaja Kallas, said: "We all want this war to end, but how it ends matters. Russia has no legal right whatsoever to any concessions from the country it invaded. This is a very dangerous moment for us all."
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'Ukraine may be facing an extremely difficult decision'
During his address, Mr Zelenskyy said he would not betray Ukraine's national interest - but warned dilemmas lie ahead.
He added: "Either a loss of dignity or the risk of losing a key partner. Either accepting a complicated list of 28 demands or enduring an extremely harsh winter, the harshest yet, with all the risks that follow.
"A life without freedom, without dignity, without justice. And all while being asked to trust someone who has already attacked us twice."
Washington has reportedly threatened to cut off intelligence sharing and weapons supplies if Kyiv refuses to accept the deal.
The US-backed proposal would require Ukraine to withdraw from territory it still controls in eastern provinces that Russia claims to have annexed - with Russia giving up smaller amounts of land it holds in other regions.
Ukraine would also be permanently barred from joining NATO, and its armed forces would be capped at 600,000 troops.
Sanctions against Russia would also be gradually lifted, with Moscow invited back into the G8 and frozen assets pooled into an investment fund.
If accepted, it would reward armed aggression. The principle, sacrosanct since the Second World War, for obvious and very good reasons, that even de facto borders cannot be changed by force, will have been trampled on at the behest of the leader of the free world.
The Kremlin will have imposed terms via negotiators on a country it has violated, and whose people its troops have butchered, massacred and raped. It is without doubt the biggest crisis in Trans-Atlantic relations since the war began, if not since the inception of NATO.
The question now is: are Europe's leaders up to meeting the daunting challenges that will follow. On past form, we cannot be sure.
The plan proposes the following:
• Land seized by Vladimir Putin's unwarranted and unprovoked invasion would be ceded by Kyiv.
• Territory his forces have fought but failed to take with colossal loss of life will be thrown into the bargain for good measure.
• Ukraine will be barred from NATO, from having long-range weapons, from hosting foreign troops, from allowing foreign diplomatic planes to land, and its military neutered, reduced in size by more than half.
And most worryingly for Western leaders, the plan proposes NATO and Russia negotiate with America acting as mediator.
Lest we forget, America is meant to be the strongest partner in NATO, not an outside arbitrator. In one clause, Mr Trump's lack of commitment to the Western alliance is laid bare in chilling clarity.
And even for all that, the plan will not bring peace. Mr Putin has made it abundantly clear he wants all of Ukraine.
He has a proven track record of retiring, rallying his forces, then returning for more. Reward a bully as they say, and he will only come back for more. Why wouldn't he, if he is handed the fortress cities of Donetsk and a clear run over open tank country to Kyiv in a few years?
Since the beginning of Trump's presidency, Europe has tried to keep the maverick president onside when his true sympathies have repeatedly reverted to Moscow.
It has been a demeaning and sycophantic spectacle, NATO's secretary general stooping even to calling the US president 'Daddy'. And it hasn't worked. It may have made matters worse.
The parade of world leaders trooping through Sharm el-Sheikh, Egypt, lavishing praise on his Gaza ceasefire plan, only encouraged him to believe he is capable of solving the world's most complex conflicts with the minimum of effort.
The Gaza plan is mired in deepening difficulty, and it never came near addressing the underlying causes of the war.
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Most importantly, principles the West has held inviolable for eight decades cannot be torn up for the sake of a quick and uncertain peace.
With a partner as unreliable, the challenge to Europe cannot be clearer.
In the words of one former Baltic foreign minister: "There is a glaringly obvious message for Europe in the 28-point plan: This is the end of the end.
"We have been told repeatedly and unambiguously that Ukraine's security, and therefore Europe's security, will be Europe's responsibility. And now it is. Entirely."
If Europe does not step up to the plate and guarantee Ukraine's security in the face of this American betrayal, we could all pay the consequences.
Sir Keir Starmer was interviewed by Rigby while the pair were in South Africa for a meeting of the G20 group of nations.
Despite the government last year indicating it was not going to raise more taxes, it appears that Wednesday's fiscal event will involve substantial increases in levies.
The 2024 Labour manifesto said: "We will ensure taxes on working people are kept as low as possible.
"Labour will not increase taxes on working people, which is why we will not increase national insurance, the basic, higher, or additional rates of income tax, or VAT."
At the start of their interview, the prime minister was asked by Rigby if it was important for politicians to "stick to their word".
Sir Keir said: "Yes, it is important that politicians stick to their word.
"They have to make decisions against a political backdrop. And, we've also got big decisions to make in the budget that's coming in just a few days time."
This caveat matches the expectations that a range of taxes are going to be increased so the government can keep its spending pledges and increase its fiscal headroom amid worsening economic headwinds.
There was chaos last week after the reported increase in income tax that many had expected to be on the way was revealed to no longer be on the cards.
Asked specifically on the manifesto commitment on tax, Sir Keir told Rigby that decisions will be made "against a very difficult backdrop".
In total, the prime minister refused 12 times to rule out tax rises.
He added it was "important to take the right decisions for our country".
Rigby pointed out in the lead-up to the budget in 2024, the prime minister was more unequivocal, saying income tax, national insurance and VAT would not all go up.
The prime minister declined to make the same promise, saying the decisions on tax will be announced on Wednesday.
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However, Sir Keir said the budget will be guided by "principles", including "fairness".
The prime minister said the three areas he is "bearing down on" are the NHS, cutting national debt and dealing with the cost of living crisis.
One tax rise that has not been ruled out is what is known as a "stealth tax rise" of freezing income tax thresholds.
Rigby highlighted that in last year's budget, Rachel Reeves said freezing thresholds will "hurt working people" - and asked the prime minister if he agreed.
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Sir Keir said: "We are going to set out our decisions.
"We will have absolutely in mind that the cost of living is the number one issue for people across the country."
Pushed again, if working people will have their taxes increased, the prime minister instead mentioned he has people who are "struggling with the cost of living" in mind when making decisions.
Gill, the former leader of Reform UK Wales and a one-time member of the European Parliament, who on Friday was jailed for 10-a-half-years, was stopped by police before boarding and had his phone seized in 2021.
While they interrogated him, his home in Anglesey was raided, with detectives discovering more electronics and cash piles of €5,000 (£4,400) and $5,000 (£3,800) respectively.
The evidence on Gill's phone would damn him – he was in contact with a pro-Russian politician in Ukraine, Oleg Voloshyn, and had agreed to boost pro-Russia viewpoints in exchange for money.
Voloshyn would dictate the statement, and Gill would repeat it – in some cases, almost word for word – in the media or the European Parliament.
In one instance, Gill appeared on the now-banned Ukrainian TV channel, 112 Ukraine, which was known for its pro-Russian stance.
In the interview, he was critical of the Ukrainian decision to open criminal proceedings against Viktor Medvedchuk, the owner of the television channel and a personal friend of Vladimir Putin.
Speaking to the outlet, he said he was "very concerned" about the investigation, and wondered whether it was meant to silence "opposition politicians".
Prosecutors said messages on Gill's phone showed that this was at his paymaster's instruction, with Voloshyn offering a "reward" if he would say that it was unacceptable to persecute a person for their political convictions.
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Voloshyn also offered the MEP €2,000 (£1,750) if he would express concern that Mr Medvedchuk could no longer mediate with Russia on Ukraine's behalf, the court heard.
He added that "V" – understood to be Mr Medvedchuk – did not believe Ukrainian President Volodymyr Zelenskyy had "true intentions to pursue a peace agenda", prosecutors said.
Sure enough, Gill appeared on 112 Ukraine saying it was "very sad" that Mr Medvedchuk felt he no longer had Mr Zelensky's backing to act as a mediator with Russia, and suggested that using him "would be a sensible thing to do".
The messages traded in innuendo, referring to the exchange of "Xmas gifts" or "postcards" instead of money.
But as the pair grew more comfortable with each other, they bargained more explicitly, with the sum of "£5k" quoted for Gill's work.
Dominic Murphy, head of Counter Terrorism Command at the Met Police, said Gill had also offered access to other MEPs.
"This is where we get into that slightly odd situation where it feels very much like a real effort to undermine democracy here," he said.
"This is Nathan Gill reaching out to individuals that he knows, who are Brits, who might be willing to be paid to go and make speeches."
Commander Murphy declined to name names, but said there was an ongoing investigation and that other people had been spoken to.
None of the pro-Brexit MEPs Gill allegedly approached have been interviewed under caution.
Police confirmed there was no evidence to suggest Reform UK leader Nigel Farage was involved.
Gill was stopped at Manchester Airport on 13 September 2021, under schedule 3 of the Counter Terrorism and Borders Security Act 2019.
He offered police no explanation for his actions and answered no comment in a March 2022 police interview.
But the 52-year-old is believed to have had financial problems.
Mr Murphy added that while Gill appeared to have pro-Russian sympathies, he was primarily motivated by money.
The ex-MEP has been jailed for 10-and-a-half years after pleading guilty to eight counts of bribery between December 2018 and July 2019.
Following an investigation by counter-terrorism police, officers said they believe Gill likely took a minimum of £40,000 in cash and was offering to introduce other British MEPs so they could be bribed.
Voloshyn was picked up by the authorities on a trip to the US in 2021, which enabled the FBI to discover his end of the conversation.
He is now believed to be in Russia, but has been sanctioned by the UK government over allegations of trying to destabilise Ukraine.
He remains wanted in both Britain and Ukraine.
A Reform UK spokesman said: "Mr Gill's actions were reprehensible, treasonous and unforgivable.
"We are glad that justice has been served and fully welcome the sentence Nathan Gill has received."
Mr Farage, the Reform UK leader, said: "An investigation into Russian and Chinese influence over British politics would be welcome."
The MP for Clacton previously described his former colleague as a "bad apple" and said he was "shocked" after Gill pleaded guilty to eight counts of bribery.
He said: "Any political party can find in their midst all sorts of terrible people.
"You can never, ever guarantee 100% that everyone you meet in your life, you shake hands with in the pub, is a good person."
Her relationship with the president has deteriorated in recent months, and she has vocally campaigned for the justice department to release all of its files concerning the convicted paedophile Jeffrey Epstein.
Mr Trump has been fiercely critical about Ms Greene on Truth Social - describing her as a "lunatic".
In a statement posted on X, she wrote: "Standing up for American women who were raped at 14, trafficked and used by rich powerful men, should not result in me being called a traitor and threatened by the President of the United States, whom I fought for."
Ms Greene went on to confirm her last day in office will be on January 5.
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