?No more summits!? he said jokingly, having only recently returned from a 10-day diplomatic tour across Asia.

Yet while that Asia trip had mixed results, forcing Mr. Obama to leave without the South Korean trade deal he had expected, the consensus with Europeans and Russians at the NATO summit in Lisbon about how to handle Afghanistan and missile defense gave him a more successful sheen ? even if ultimate success, particularly in Afghanistan, remains problematic.

Mr. Obama was able to lead on a world stage in a way that he has not been able to do lately at home. He did so with public and private assistance from his European and Russian counterparts, many of whom called the summit meeting historic. Acutely aware of his problems at home after the drubbing Democrats took in the midterm elections ? most manifest in Senate Republicans? resistance to the New Start nuclear arms reduction treaty with Russia ? the other leaders seemed almost to go out of their way to buoy Mr. Obama.

Their help was not merely volunteered; administration officials actively sought it. ?Throughout the summit, there was intense lobbying by the administration to win support for the ratification process,? said the Czech defense minister, Alexandr Vondra.

And while a two-hour gathering with the European Union was a footnote to the weekend NATO summit meeting that preceded it, the leaders there likewise hailed their exchanges over economic and security concerns.

?I have been to many summits,? the European Commission president, José Manuel Barroso, said afterward, but Lisbon was more ?intimate, informal? and ?a real exchange about the priorities? instead of mere note-reading ? and he gave credit to Mr. Obama.

In the end, then, the more common diplomatic dynamic was flipped: Instead of foreign leaders taking advantage of a weakened counterpart, they rallied to his aid ? for their own interests as much as Mr. Obama?s, given the economic and military stakes.

In particular, they gave Mr. Obama ammunition in his Senate battle for the New Start treaty. He collected a series of supportive statements from European leaders ? from Chancellor Angela Merkel of Germany to leaders of former Soviet bloc nations, who remain deeply suspicious of Russia and wary of Mr. Obama?s ?reset? policy for warmer relations with Russia.

At a news conference after the NATO session, Mr. Obama said, ?Unprompted, I have received overwhelming support from our allies here that Start ? the New Start treaty ? is a critical component to U.S. and European security.?

The endorsers, he added, include ?those who live right next to Russia, who used to live behind the Iron Curtain, who have the most cause for concern with respect to Russian intentions and who have uniformly said that they will feel safer and more secure if this treaty gets ratified.?

Like the Eastern Europeans, NATO leaders more broadly agreed, in effect, that the Mr. Obama?s ?reset? relationship with Russia had enabled a parallel reset of their own ties with the former Communist bloc leader. The NATO-Russia Council meeting was the first since Russia went to war with Georgia to its south in 2008.

Mr. Obama also made progress drawing Russia into cooperating with, rather than opposing, a new missile defense network in Europe aimed at countering any future threat from Iran. The White House hopes that Russian cooperation could undercut the argument of conservative critics of New Start that the treaty would crimp missile defense plans.

As some Europeans saw it, President Dmitri A. Medvedev of Russia also seemed to respond to Mr. Obama?s tenuous position at home. Administration officials said that as recently as three weeks ago it was not clear Mr. Medvedev would come, and that days before Lisbon, there was no agreement on a joint statement to issue.

When Mr. Obama had to leave the NATO-Russia meeting for a separately scheduled meeting with President Hamid Karzai of Afghanistan, he had advisers set up a private talk with Mr. Medvedev ? no aides, just one translator.

An official to whom Mr. Obama described their conversation afterward, and who would speak only on the condition of anonymity under White House rules, said it was ?very cordial? though Mr. Obama raised their differences over Georgia. As for New Start?s ratification, Mr. Medvedev expressed confidence ?in the president getting it done,? the official said.