President Volodymyr Zelensky of Ukraine told leaders of the European Union’s 27 member states in Brussels on Thursday that his country desperately needed their support for his “victory plan,” which he maintains could end the war no later than next year, but which it is unclear how much Ukraine’s allies will embrace.

Mr. Zelensky made the impassioned plea on his latest trip abroad as he tries to attract sustained international support for Ukraine, two and a half years into the war, and as Ukrainian forces are steadily losing ground to Russian troops. He had hoped to present the plan to European leaders in Germany earlier in the month, but that gathering was postponed when President Biden canceled his participation to deal with the effects of Hurricane Milton.

“You all know Russia’s psychology,” Mr. Zelensky told E.U. leaders on Thursday. “Russia will resort to diplomacy only when it sees that it cannot achieve anything by force.”

Mr. Zelensky is scheduled to speak at a news conference with Mark Rutte, the head of NATO, later on Thursday and will make the case for Ukraine’s accession into the military alliance — a key point in his proposals.

The “victory plan” also calls for the West to lift restrictions on Kyiv’s use of Western-delivered missiles to strike ammunition depots and other military facilities inside Russia, and to share more satellite data that Ukraine can use to identify and strike Russian targets.

The Ukrainian leader laid out the plan for the first time in public on Wednesday in a speech to his country’s Parliament, an attempt to rally support at home around the idea that Kyiv can turn the tide on the battlefield. Ukraine is heading into what looks to be another difficult winter, with Russia stepping up its attacks on energy infrastructure.