Moscow’s rejection of an immediate ceasefire in Ukraine appears to have put a summit between Donald Trump and Vladimir Putin in jeopardy, diplomats said on Tuesday, after a preparatory meeting between the top US and Russian diplomats was postponed.

European leaders called on Washington on Tuesday to hold firm in demanding an immediate ceasefire in Ukraine, with present battle lines to serve as the basis for any future talks. Moscow has long demanded that Ukraine agree to cede more territory before any ceasefire.

Trump, who last week spoke by phone to Putin and met Ukrainian President Volodymyr Zelenskiy, has said he aims to hold a summit with the Russian leader in the Hungarian capital Budapest within two weeks in a push to end the war.

But summit preparations have hit a snag, with the sides postponing a preparatory meeting between US Secretary of State Marco Rubio and Russian Foreign Minister Sergei Lavrov, expected to take place in Budapest on Thursday.

Lavrov and Rubio spoke by phone on Monday. Lavrov’s deputy, Sergei Ryabkov, said on Tuesday it was premature to speak about the timing of any face-to-face meeting between them.

‘I guess the Russians wanted too much’

Neither side has publicly abandoned plans for Trump to meet Putin, and efforts to organise a summit in Hungary still appear to be under way. Hungary’s foreign minister, Peter Szijjarto, was in Washington on Tuesday, where he posted on Facebook: “We have some serious days ahead”.

But two senior European diplomats said the postponement of the Rubio-Lavrov meeting was a sign the Americans could be reluctant to go ahead with a Trump-Putin summit unless Moscow yields from its demands.

“I guess the Russians wanted too much and it became evident for the Americans that there will be no deal for Trump in Budapest,” said one.

The Russians “haven’t at all changed their position, and are not agreeing to ‘stop where they are’,” said the second diplomat. “And I assume Lavrov gave the same spiel, and Rubio was like: ‘See you later’.”

Europeans concerned trump will get no concessions

Ukraine’s European allies have been concerned that Trump could meet Putin for a second time without getting any serious concessions from the Russian leader, after Putin rebuffed Trump’s call for a ceasefire at a summit in Alaska in August.

In a statement on Tuesday, the leaders of European powers including Britain, France, Germany and the EU, said they “strongly support President Trump’s position that the fighting should stop immediately, and that the current line of contact should be the starting point of negotiations”.

Trump has often changed his emphasis in public when speaking about Ukraine. But last Friday after his meeting with Zelenskiy at the White House he explicitly endorsed the position that a ceasefire should start with forces at their present positions.

Reuters and other news organisations reported that Trump’s meeting with Zelenskiy behind closed doors was contentious, with the US president repeatedly using profanity and pushing Zelenskiy to accept some Russian demands.

But Zelenskiy has painted the meeting as a success because it ended with Trump publicly backing a ceasefire at the present lines, Kyiv’s longstanding position.

European leaders are due to meet this week with Zelenskiy as their guest, first at an EU summit and then at a meeting of the “coalition of the willing” countries discussing a security force to guarantee a post-war settlement in Ukraine. Russia rejects such an international security force.

The choice of Budapest as a venue for a Putin-Trump meeting is contentious within the EU, where Hungary’s Prime Minister Viktor Orban is an outlier as one of the few leaders to maintain warm relations with Russia.

Any trip to Budapest would require Putin to fly through the airspace of other EU countries. Poland said on Tuesday it could force Putin’s plane down and arrest him on an international warrant if he flies over its territory, but Bulgaria said Putin could use its airspace to reach the meeting.