The European leaders of Britain, Germany, France, Italy, Finland and NATO hope to shore up Zelenskiy at a crucial diplomatic moment in the war and prevent any repetition of the bad-tempered Oval Office encounter between Trump and Ukraine's leader in February.
Trump will meet first with Zelenskiy at 1:15pm on Monday (3:15am AEST Tuesday) in the Oval Office and then with all the European leaders together in the White House's East Room at 3pm local time.
After rolling out the red carpet for Russian President Vladimir Putin in Alaska on Friday, Trump said an agreement should be struck to end the 42-month-long war which has killed tens of thousands and displaced millions.
"Russia is a very big power, and they're not," Trump said of Ukraine afterwards.
However, Zelenskiy has already all but rejected the outline of Putin's proposals at that meeting, including for Ukraine to give up the rest of its eastern Donetsk region, of which it currently controls a quarter.
"We need real negotiations, which means we can start where the front line is now," the Ukrainian leader said in Brussels on Sunday, adding that his country's constitution made it impossible for him to give away territory.
More concerning for him is the fact that Trump, who previously favoured Kyiv's proposal for an immediate ceasefire to conduct deeper peace talks, reversed course after the summit and indicated support for Russia's favoured approach of negotiating a comprehensive deal while fighting rumbles on.
"I am grateful to the President of the United States for the invitation. We all equally want to end this war swiftly and reliably," Zelenskiy said on X after arriving in Washington late on Sunday.
"Russia must end this war — the war it started. And I hope that our shared strength with America and with our European friends will compel Russia to real peace."
The outline of Putin's proposals, reported by Reuters earlier, appears impossible for Zelenskiy to accept.
Ukrainian forces are deeply dug into the Donetsk region, whose towns and hills serve as a crucial defensive zone to stymie Russian attacks.
As part of any peace deal, Kyiv wants security guarantees sufficient to deter Russia, which took Ukraine's Crimean peninsula in 2014 and launched a full invasion in 2022, from attacking again.
Fearing that they would be shut out of the conversation after a summit to which they were not invited, European leaders held a call with Zelenskiy on Sunday to align on a common strategy for the meeting with Trump.
The presence of six allies to back Zelenskiy may alleviate painful memories of Zelenskiy's last Oval Office visit.
"It's important for the Europeans to be there: (Trump) respects them, he behaves differently in their presence," Oleksandr Merezhko, a Ukrainian lawmaker told Reuters.
US Secretary of State Marco Rubio, speaking to CBS, dismissed the idea that the European leaders were coming to Washington to protect Zelenskiy.
"They're not coming here tomorrow to keep Zelenskiy from being bullied. They're coming here tomorrow because we've been working with the Europeans," he said. "We invited them to come."
Relations between Kyiv and Washington, once extremely close, have been rocky since Trump took office in January.
However, Ukraine's pressing need for US weapons and intelligence sharing, some of which have no viable alternative, has forced Zelenskiy and his allies on the continent to appease Trump, even when his statements appear contradictory to their objectives.
On the battlefield Russia has been slowly grinding forward, pressing home its advantages in men and firepower. Putin says he is ready to continue fighting until his military objectives are achieved.
Ukraine hopes that the changing technological nature of the war and its ability to inflict massive casualties on Moscow will allow it to hold out, supported by European financial and military aid even if relations with Washington collapse.
