He stood alone for months in blocking a European aid package for Ukraine worth $52 billion but then meekly folded. He refused to accept Sweden as a new member of NATO for more than a year before eventually bowing to pressure from bigger countries and giving his unconditional assent.

The same pattern repeated itself on Tuesday when Prime Minister Viktor Orban of Hungary made a surprise visit to Kyiv to meet the Ukrainian president, Volodymyr Zelensky, taking a path well trodden for more than two years by other European leaders but previously shunned by Mr. Orban.

Hungarian officials explained the previously unannounced trip as an effort to promote “peace” — Hungary’s euphemism for a settlement built on Ukrainian capitulation to Russian demands. Many observers saw it instead more as a move by Mr. Orban to try to end his isolation over Ukraine on the European stage.

Zsomber Zeold, a former Hungarian diplomat and foreign policy expert in Budapest, said the visit had “come as a complete surprise to me and many others” given that Mr. Orban has staked out such a hostile position toward Ukraine for so long. “The most plausible explanation,” Mr. Zeold said, is that “he wants to build up some kind of credibility within the European Union as not just a one-sided, pro-Russian actor.”

Hungary this week took over the rotating presidency of the European Union promising to “make Europe great again.” But the presidency is largely a clerical position, and Mr. Orban’s oft-repeated vow to “take over Brussels” has rested instead on a calculation that elections last month for the European Parliament would make Hungary’s governing Fidesz party a powerful new center of gravity for like-minded nationalist forces in the continental body.

That hope, however, has so far been hobbled by Mr. Orban’s reputation as the European bloc’s most Kremlin-friendly leader — a position with which only a few marginal figures want to be associated.

Peter Kreko, the director of Political Capital, a research group in Budapest that is often critical of the Hungarian leader, described Mr. Orban’s the trip to Kyiv as a “wise, unexpected surprise that can improve his chances of getting closer to the E.U. mainstream” and forging an alliance with conservatives like Giorgia Meloni, the Italian prime minister. While Ms. Meloni agrees with Mr. Orban on the need to tightly restrict immigration and protect national sovereignty, she has been put off by his pro-Kremlin stand on Ukraine.

“He knows that visiting Zelensky is code for being a ‘member of the club’, and he would like to send a strong message to E.U. leaders that he is in the club even if he plays the outsider many times,” Mr. Kreko said.

When Hungary last week announced the formation of a new right-wing alliance in the European Parliament called Patriots for Europe, Mr. Orban declared it the start of a “new era” of “peace, security and development” instead of “war, migration and stagnation” that “will change European politics.”

But the new Hungarian-led legislative alliance, which Mr. Orban predicted “will soon be the strongest right-wing political group in Europe,” only managed to attract two small populist parties from Austria and the Czech Republic. A tiny right-wing Portuguese party has since said it will join, too. Another possible addition is the far-right Italian party of Matteo Salvini, an outspoken fan of President Vladimir V. Putin of Russia, who is struggling to overcome a dismal performance in the Europe’s June elections.

Europe’s most powerful nationalist parties have so far all stayed away, reducing Mr. Orban’s chances of becoming a central figure on the surging populist right.

Law and Justice, the former governing party in Poland, which has a far bigger economy, military and population than Hungary, shares Mr. Orban’s hostility to immigration and the Brussels bureaucracy. But it declined to join the new alliance, largely because of Hungary’s stand on the war in Ukraine.

Ms. Meloni of Italy has also shown no interest in joining forces with Hungary in the European Parliament and is sticking with her own group in the assembly.

By traveling to Ukraine, Mr. Orban “is trying to break out of political no man’s land in the E.U., and showing a more open approach toward Kyiv would be key in this regard,” said Edit Zgut-Przybylska, an assistant professor at the Polish Academy of Sciences who has written extensively about Russian influence in Hungary.

Speaking in Kyiv on Tuesday, Mr. Orban repeated his calls for “peace” but avoided any suggestion that achieving it depended on Ukraine’s giving up. The Hungarian news agency MTI said Mr. Orban called for a “time-bound cease-fire, which gives an opportunity to speed up peace talks.”

Unian, a Ukrainian news outlet, quoted Mr. Orban as saying “peace is an important issue. The war in which you are living now has a very intense effect on the security of Europe.” He made no public criticism of Mr. Zelensky over the treatment of Ukraine’s Hungarian minority, previously a major bone of contention often raised by Mr. Orban, and instead thanked Mr. Zelensky for listening to his views on a possible cease-fire.

Professor Zgut-Przybylska said Mr. Orban’s trip “does not mean that the Hungarian government will make a U-turn in politics.” Instead, it fit into what the prime minister has himself described as Hungary’s “peacock dance”: a policy of fluttering feathers to different sides depending on the moment.

“Orban has been playing this ‘peacock’ dance for a decade,” she said, “and Hungary’s energy dependency on Russia will remain stronger than ever.”

Russia, perhaps worried that it could be losing its most reliable friend in the European Union, played down the significance of Mr. Orban’s visit. Dmitri S. Peskov, the Kremlin’s spokesman, was quoted by Tass news agency as saying Mr. Orban’s presence in Kyiv did not reflect a change in Hungary’s position but only its responsibilities after assuming the European Union’s rotating presidency. “We don’t expect anything,” Mr. Peskov said.

An early sign that Mr. Orban wants to shed his toxic image as a Kremlin puppet, said Mr. Zeold, the former diplomat, came last month when he gave a warm welcome in Budapest to the NATO secretary general, Jens Stoltenberg, a robust supporter of military assistance to Ukraine.

Mr. Orban assured Mr. Stoltenberg that he would not veto NATO support for Ukraine at a summit this month of alliance leaders in Washington. He still insisted that Hungary would not provide funds or military personnel for any joint assistance efforts. But the promise not to play the role of a spoiler at the summit calmed worries that Hungary might torpedo proposals for a new system to provide more predictable, long-term security assistance and military training to Ukraine.

Positioning himself as Europe’s champion of “peace” against what he derides as Europe’s “warmongers” has played well politically at home for Mr. Orban. His Fidesz party won a landslide election victory, its fourth in a row, in 2022 after smearing the main opposition leader as a reckless leader bent on sending Hungarians to fight against Russia in Ukraine. That was a lie but, repeated noisily by news media outlets controlled by Mr. Orban’s party, it helped destroy the opposition.

In the run-up to last month’s European Parliament election, Fidesz warned that Europe’s support for Ukraine risked triggering World War III and railed against what it said were proposals in Brussels to impose mandatory military conscription across Europe. No such proposals existed, but the fear stirred up by Fidesz helped the party win the vote in Hungary for the European legislature, though a strong showing by an upstart conservative rival reduced the scale of Mr. Orban’s victory.

Conscription, the E.U.’s foreign affairs chief, Josep Borrell, said, “is a national decision” and not something Brussels could ever impose.

Domestic political expediency, however, has crimped Mr. Orban’s appeal beyond Hungary’s borders. His most vocal supporters abroad have been right-wing Americans like Donald J. Trump. In Europe, only Slovakia has been vociferous in opposing support for Ukraine.

And that, said Mr. Zeold, is a problem for Mr. Orban, whose soaring ambitions reach far beyond just Hungary’s less than 10 million people.

“The Hungarian domestic political scene is too small for Orban,” Mr. Zeold said. “He wants to play on a bigger playing field. And that is the E.U.”

Marc Santora contributed reporting.