By DASHA LITVINOVAAND ISOBEL KOSHIW | THE ASSOCIATED PRESS

Diplomats face an uphill battle to reconcile Russian and Ukrainian "red lines" as a renewed U.S.-led push to end the war gathers steam, with Ukrainian officials attending talks in the U.S. over the weekend and Washington officials expected in Moscow early this week.

U.S. President Donald Trump's peace plan became public last month, sparking alarm that it was too favorable to Moscow. It was revised following talks in Geneva between the U.S. and Ukraine a week ago.

Ukraine's President Volodymyr Zelenskyy has said the revised plan could be "workable." Russian President Vladimir Putin called it a possible "basis" for a future peace agreement. Trump said Sunday "there's a good chance we can make a deal."

Still, officials on both sides indicated a long road ahead as key sticking points - over whether Kyiv should cede land to Moscow and how to ensure Ukraine's future security-appear unresolved.

Trump representatives met the Ukrainian officials over the weekend and plan to meet with the Russians in coming days.

Ukraine's national security council head Rustem Umerov, the head of Ukraine's armed forces Andrii Hnatov, presidential adviser Oleksandr Bevz and others met with U.S. officials for about four hours on Sunday. U.S. Secretary of State Marco Rubio said the session was productive, but more work remains. Umerov praised the U.S. for its support but offered no details.

Zelenskyy's former chief of staff and former lead negotiator for Ukraine, Andrii Yermak, resigned Friday amid a corruption scandal and is no longer part of the negotiating team. It was only a week ago that Rubio met with Yermak in Geneva, resulting in a revised peace plan.

Trump said last week that he would send his envoy Steve Witkoff to Russia. Kremlin spokesman Dmitry Peskov confirmed Monday that Putin will meet Witkoff on Tuesday afternoon.

Eager to please Trump, Kyiv and Moscow have ostensibly welcomed the peace plan and the push to end the war. But Russia has continued attacking Ukraine and reiterated its maximalist demands, indicating a deal is still a way off.

Putin implied last week that he will fight as a long as it takes to achieve his goals, saying that he will stop only when Ukrainian troops withdraw from all four Ukrainian regions that Russia illegally annexed in 2022 and still doesn't fully control. "If they don't withdraw, we'll achieve this by force. That's all," he said.

The plan, Putin said, "could form the basis for future agreements," but it is in no way final and requires "a serious discussion."

Zelenskyy has refrained from talking about individual points, opting instead to thank Trump profusely for his efforts and emphasizing the need for Europe -whose interests are more closely aligned with Ukraine's - to be involved. He also has stressed the importance of robust security guarantees for Ukraine.

Zelenskyy has said repeatedly that giving up territory is not an option. Zelenskyy also maintains that NATO membership is the cheapest way to guarantee Ukraine's security, and NATO's 32 member countries said last year that Ukraine is on an "irreversible" path to membership. Since he took office, Trump has made it clear that NATO membership is off the table.