WASHINGTON — President Bush assured Georgia’s president, Mikhail Saakashvili, today that he will press at the NATO summit next month to put Georgia on track for membership in the alliance.

Mr. Bush also called for a peaceful resolution of differences with the republic’s two breakaway regions of Abkhazia and South Ossetia.

Though Mr. Bush has been a strong booster of Georgia’s NATO hopes, he may not be able to offer Mr. Saakashvili more than encouragement when he attends the summit being held April 2-4 in Bucharest, Romania.

Georgia’s chances of joining a program that would prepare it for eventual membership will hinge on winning unanimous support of the 26 member countries. Some Western leaders, including Chancellor Merkel of Germany, have misgivings about moving Georgia a step closer to membership.

Mr. Bush will be looking to persuade the NATO allies, but his prospects are unclear.

“I believe that NATO benefits with a Georgia membership, I believe Georgia benefits from being a part of NATO,” Mr. Bush said at a joint appearance with Mr. Saakashvili following a White House meeting.

Russia has opposed NATO’s eastward expansion and seems particularly angered about the prospect of membership for Georgia and Ukraine. The leaders of both former Soviet republics have annoyed Moscow by turning toward the West.

“I have to thank you, Mr. President, for your unwavered support for our freedom, for our democracy, for our territorial sovereignty and for protecting Georgia’s borders and for Georgia’s NATO aspirations,” Mr. Saakashvili told Mr. Bush.

The boost for Mr. Saakashvili’s NATO aspirations comes only months after America and other Western countries criticized Georgia for a brutal police crackdown November 7 against an opposition rally in Tbilisi. Following the violence, Mr. Saakashvili called an early presidential vote to ease tensions, and America has praised the elections. Opposition leaders have accused Mr. Saakashvili of stealing the January 5 presidential election in which he was re-elected with just over half of the vote.

Today, about 1,500 opponents of Mr. Saakashvili held a demonstration outside the American Embassy in Tblisi.

“We are demanding that the United States stop supporting Saakashvili, who is an illegitimate president,” an opposition leader, Levan Gachechiladze, said. “The United States must see Georgia not just as an important territory from the point of view of geopolitics, but a country that strives to build democratic society and must have free elections.”

The small nation lies on a key export route for Caspian Sea oil exports to the West, contributing to its role in a struggle for regional sway between Russia and America.

Since Mr. Saakashvili was first elected in 2004, the 40-year-old American-educated lawyer has helped transform Georgia into a country with a growing economy and aspirations of joining the European Union as well as NATO.

He has been a staunch ally of America. Today, Mr. Bush thanked him for the contingent of 2,000 troops currently serving in Iraq.

“The citizens of Georgia must know that the troops that have been provided there are brave, courageous professionals, and have made a significant difference,” Mr. Bush said.

He also alluded to international concern over Georgia’s two breakaway republics.

“We talked about the need for there to be peaceful resolutions of conflicts, while recognizing the territorial integrity and sovereign borders of Georgia,” Mr. Bush said.

Friction over the two regions has flared recently because Russia has warned that Kosovo’s declaration of independence from Serbia last month, and the West’s recognition of it, could fuel other separatist movements, including those in Georgia.

But yesterday, Russia took a step toward easing tensions with Georgia by agreeing to restore air travel between the two countries more than 17 months after imposing a sweeping transport blockade.