LONDON — The White House said it’s is “very optimistic” ahead of special envoy Steve Witkoff’s meeting in Moscow on Tuesday with Russian President Vladimir Putin, as U.S. officials continue their push to end Russia’s war against Ukraine.

The high-stakes sit-down follows a series of meetings between top U.S. and Ukrainian officials, during which the parties sought to revise the original peace-plan proposal presented by the Trump administration to Ukraine last month.

Witkoff and other top U.S. officials — including President Donald Trump’s son-in-law Jared Kushner and Secretary of State Marco Rubio — met on Sunday in Florida with a Ukrainian delegation to find a deal to end the war that Ukraine and Russia might accept.

“I think the administration feels very optimistic,” White House press secretary Karoline Leavitt told reporters on Monday, following the Florida meeting. “They had very good talks with the Ukrainians in Florida. And now, of course, Special Envoy Witkoff is on his way to Russia.”

The Kremlin on Monday said a meeting between Witkoff and Putin was scheduled for Tuesday.

“The president will hold several closed-door meetings today in preparation for the Russian-American contacts,” Kremlin spokesperson Dmitry Peskov told reporters in Moscow on Monday.

There is little expectation Putin will agree to a deal. The Russian leader has already signaled he will not compromise, last week making hardline remarks where he repeated his demands that Ukraine withdraw from territory he claims and saying it is “pointless” to negotiate with Ukrainian President Volodymyr Zelenskyy.

Putin on Monday claimed without evidence that Russian forces had taken control of two Ukrainian cities where intense fighting has been happening for weeks in the eastern part of the country.

Ukrainian President Volodymyr Zelenskyy, who was not directly involved with the talks in Florida, met on Monday with French President Emmanuel Macron in Paris. He landed on Tuesday in Dublin, where he’s expected to meet with Taoiseach Micheál Martin, the Irish prime minister.

“Our engagement today was substantive and important — above all, focused on the steps that bring a just peace closer,” he said on social media after his meeting with Macron. “Now actions are needed that will truly change the course of the war and lead it to a just peace, to a real end — the kind we need. And it is important that all partners who can genuinely help do so.”

As Zelenskyy pushed for European unity against Russian aggression, members of his delegation in Florida were sending updates on what was being discussed. He said there were still several “tough issues” to work through in the negotiations, but did not elaborate. Ukraine potentially ceded some of its property to Russia was thought to be part of the talks.

Zelenskyy on Monday said he, Macron and British Prime Minister Keir Starmer had again been briefed by Witkoff and the head of the Kyiv delegation, Rustem Umerov, the secretary of Ukraine’s National Security and Defense Council. 

“Over two very productive days in the United States, we held many hours of meetings and negotiations,” Umerov said in a social media update on Monday. “We achieved significant progress, although some issues still require further refinement.”

Leavitt did not on Monday detail what the U.S. expected to happen during the negotiations in Moscow, instead deferring to those who would be at the meeting.

“We’ve put points on paper. Those points have been very much refined,” she said. “But as for the details, I will let the negotiators negotiate. But we do feel quite good, and we’re hopeful that this work can finally come to an end.”

ABC News’ Emily Chang and Patrick Reevell contributed to this report.