WASHINGTON, Dec 4 (Reuters) - Advisers to Donald Trump publicly and privately are floating proposals to end the Ukraine war that would cede large parts of the country to Russia for the foreseeable future, according to a Reuters analysis of their statements and interviews with several people close to the U.S. president-elect.

The proposals by three key advisers, including Trump's incoming Russia-Ukraine envoy, retired Army Lieutenant-General Keith Kellogg, share some elements, including taking NATO membership for Ukraine off the table.

Trump's advisers would try forcing Moscow and Kyiv into negotiations with carrots and sticks, including halting military aid to Kyiv unless it agrees to talk but boosting assistance if Russian President Vladimir Putin refuses.

Trump repeatedly pledged during his election campaign to end the nearly three-year-old conflict within 24 hours of his Jan. 20 inauguration, if not before then, but has yet to say how.

Analysts and former national security officials voice grave doubts Trump can fulfill such a pledge because of the conflict's complexity.

Taken together, however, his advisers' statements suggest the potential contours of a Trump peace plan.

Ukrainian President Volodymyr Zelenskiy, facing manpower shortages and growing territorial losses, has indicated that he may be open to negotiations.

While still intent on NATO membership, he said this week that Ukraine must find diplomatic solutions to regaining some of its occupied territories.

But Trump may find Putin unwilling to engage, analysts and former U.S. officials said, as he has the Ukrainians on the back foot and may have more to gain by pursuing further land grabs.

"Putin is in no hurry," said Eugene Rumer, a former top U.S. intelligence analyst on Russia now with the Carnegie Endowment for International Peace think tank.

The Russian leader, he said, shows no readiness to drop his conditions for a truce and talks, including Ukraine abandoning its NATO quest and surrendering the four provinces Putin claims as part of Russia but does not fully control, a demand rejected by Kyiv.

Putin, Rumer said, likely will bide his time, take more ground and wait to see what, if any, concessions Trump may offer to lure him to the negotiating table.

Reuters reported in May that Putin was ready to halt the war with a negotiated ceasefire that recognized current front lines but was ready to fight on if Kyiv and the West did not respond.

Russia already controls all of Crimea, having unilaterally seized it from Ukraine in 2014 and has since taken about 80% of the Donbas - which is comprised of Donetsk and Luhansk - as well as more than 70% of Zaporizhzhia and Kherson, and small parts of the Mykolaiv and Kharkiv regions.

MORE THAN ONE PLAN

As of last week, Trump had yet to convene a central working group to flesh out a peace plan, according to four advisers who requested anonymity to describe private deliberations. Rather, several advisers have pitched ideas among themselves in public forums and - in some cases - to Trump, they said.

Ultimately, a peace agreement will likely depend on direct personal engagement between Trump, Putin and Zelenskiy, the advisers said.

Kremlin spokesman Dmitry Peskov said it was “not possible to comment on individual statements without having an idea of the plan as a whole.”

Trump spokesperson Karoline Leavitt noted that Trump has said he "will do what is necessary to restore peace and rebuild American strength and deterrence on the world stage."

A Trump representative did not immediately respond to a follow-up question about whether the president-elect still plans to resolve the conflict within a day of taking office.

The Ukrainian government did not immediately respond to a request for comment.

One former Trump national security official involved in the transition said there are three main proposals: the outline by Kellogg, one from Vice President-elect JD Vance and another advanced by Richard Grenell, Trump's former acting intelligence chief.

Kellogg's plan, co-authored with former National Security Council official Fred Fleitz and presented to Trump earlier this year, calls for freezing the current battle lines.

Kellogg and Fleitz did not respond to requests for comment. Their plan was first reported by Reuters.

Trump would supply more U.S. weapons to Kyiv only if it agreed to peace talks. At the same time, he would warn Moscow that he would increase U.S. aid to Ukraine if Russia rejected negotiations. NATO membership for Ukraine would be put on hold.

Ukraine also would be offered U.S. security guarantees, which could include boosting weapons supplies after an accord is struck, according to that proposal.

In a June interview with Times Radio, a British digital station, Sebastian Gorka, one of Trump's incoming deputy national security advisers, said Trump had told him he would force Putin into talks by threatening unprecedented weapons shipments to Ukraine if Putin refused.

Gorka, reached by phone, called Reuters "fake news garbage" and declined to elaborate.

Vance, who as a U.S. senator has opposed aid to Ukraine, floated a separate idea in September.

He told U.S. podcaster Shawn Ryan that a deal likely would include a demilitarized zone at the existing front lines that would be "heavily fortified" to prevent further Russian incursions. His proposal would deny NATO membership to Kyiv.

Representatives for Vance did not make him available for comment, and he has yet to offer additional details.

Grenell, Trump's former ambassador to Germany, advocated the creation of "autonomous zones" in eastern Ukraine during a Bloomberg roundtable in July but did not elaborate. He also suggested NATO membership for Ukraine was not in America's interest.

Grenell, who did not respond to a request for comment, has yet to secure a position in the new administration, although he still has Trump's ear on European issues, a senior Trump foreign policy adviser told Reuters.

That person said Grenell was one of the few people at a September meeting in New York between Trump and Zelenskiy.

PUSHBACK LIKELY

Elements of the proposals would likely face pushback from Zelenskiy, who has made a NATO invitation part of his own “Victory Plan,” and from European allies and some U.S. lawmakers, say analysts and former national security officials.

Last week, Ukraine's foreign minister sent a letter to his NATO counterparts urging them to issue a membership invitation at a foreign ministers' meeting on Tuesday.

Some European allies have expressed a willingness to ramp up aid to Ukraine and U.S. President Joe Biden is continuing to send weapons. That could cost Trump some leverage to push Kyiv to the table.

The Kellogg plan, which hinges on increasing aid for Ukraine if Putin does not come to the table, could face blowback in Congress, where some of Trump's closest allies oppose additional military aid for the Eastern European nation.

"I don’t think anybody has any realistic plan for ending this," said Rumer, the former U.S. intelligence officer.

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Reporting by Gram Slattery and Jonathan Landay in Washington; Additional reporting by Tom Balmforth in Kyiv and Guy Faulconbridge in Moscow; Editing by Ross Colvin and Howard Goller