BRATISLAVA, Slovakia – President Bush and President Putin have set the stage for what could be their most acrimonious exchange to date when they meet tomorrow in the capital of this former Warsaw Pact country.

Facing increasing pressure to take a harder line on Russia’s faltering record on democracy, Mr. Bush surprised observers by criticizing the country Monday at the outset of his European tour. In a speech in Brussels, Mr. Bush called on the Russian government “to renew a commitment to democracy and the rule of law” and called on Russia to stand for “a free press, a vital opposition, the sharing of power, and the rule of law.”

The Kremlin has been equally confrontational in the run-up to the Bush-Putin summit, with Mr. Putin late last week discounting American fears that Iran is seeking nuclear weapons and Moscow announcing it would go ahead with sales of missiles to Syria and assault rifles to Venezuela despite vocal U.S. objections.

Experts are convinced the summit will set the tone for relations for years to come.

“It seems that Russian-American relations are at a turning point,” the director of Moscow’s prestigious U.S.A. and Canada Institute, Sergei Rogov, said. “The Bratislava meeting could be the event that either provides new momentum for development or leaves relations thoroughly soured.”

Yesterday, Messrs. Bush and Putin offered conflicting assessments of democracy in Russia, the Associated Press reported.

In Brussels, Mr. Bush said: “A constructive relationship allows me to remind him that I believe Russia is a European country and European countries embrace those very same values that America embraces. I’m confident that can be done in a cordial way.” It was the second day in a row Mr. Bush had openly criticized the state of Russia’s democracy.

In Moscow, Mr. Putin defended his approach but was conciliatory. When he was asked if he anticipated unpleasant questions from Mr. Bush, Mr. Putin said: “Russia chose democracy 14 years ago not to please anyone, but for its own sake, for the sake of the nation and its citizens.” Speaking to Slovak reporters, he added: “Naturally, basic principles and institutions of democracy must be adapted to today’s realities of Russian life, to our traditions and history.”

A number of pressing issues are on the official agenda for the summit meeting, including joint action against terrorism and weapons proliferation, and increased cooperation on tapping Russia’s vast energy resources. But it is growing alarm over the state of Russian democracy that is expected to grab the most attention.

Critics of Russia have been saying the meeting will mark the first test of the promise laid out in Mr. Bush’s inauguration speech last month to promote democracy and to confront “every ruler and every nation” about respecting freedom and “ending tyranny in the world.”

Mr. Bush, who once famously said he looked into Mr. Putin’s eyes and saw the man’s soul, has until recently shied away from criticizing the Russian president, instead emphasizing their personal friendship. But a chorus of voices, both conservative and liberal, has recently been calling on Mr. Bush to take Mr. Putin to task for an authoritarian resurgence. In recent years, the Kremlin has stifled the independent media, sent political opponents to prison or forced them into exile, renationalized the country’s main oil company, abolished elections for regional governors, and tightened its control over the Parliament. Human-rights groups also accuse Russian forces of carrying out widespread abuses in Chechnya, where the Kremlin is struggling with separatist rebels it accuses of links with international terrorists.

“I do not think that it is accurate to say democracy is in retreat in Russia. Democracy has been assassinated in Russia,” the president of the Project on Transitional Democracies, Bruce Jackson, recently told the U.S. Senate Committee on Foreign Relations.

On Friday, two of the most respected senators, John McCain, Republican of Arizona, and Joseph Lieberman, Democrat of Connecticut, introduced a measure calling for Russia to be suspended from the Group of Eight industrialized nations because of its retreat from democracy.

In a letter that the pro-democracy group Freedom House published last week, an international group of scholars, human-rights leaders, democracy activists, and former government officials appealed to Mr. Bush to “raise a number of urgent human rights concerns” during the meeting.

In the most recent edition of the Weekly Standard, a Stanford University Russia professor, Michael McFaul, and a George Washington University professor, James Goldgeier, wrote, “calling for freedom’s advance on Inauguration Day is one thing; saying the same to Putin a month later is another, and a much more difficult, thing.

“If Bush goes to Bratislava and fails to reiterate the sentiments of his inaugural address in public appearances with Putin,” they wrote, “then the critics were right and authoritarian leaders everywhere can sleep easy.”

The Kremlin has signaled its displeasure with the attacks in a series of recent moves in defiance of the White House.

Washington has repeatedly called on Moscow to drop plans to ship atomic fuel to a Russian-built nuclear reactor in Iran, over fears that the supplies could be used to make a nuclear bomb. At a meeting Friday with Iran’s chief nuclear negotiator, Hassan Rowhani, Mr. Putin said Russia was convinced Iran was not developing nuclear weapons and vowed to continue cooperating with Tehran “in all spheres.” Two days earlier, Russia’s defense ministry confirmed that it was negotiating the sale of Strelets air-defense systems to Syria, which America accuses of sponsoring terrorism.

In response to complaints about the Kremlin’s activities, Russian officials accuse critics of trying to stir up Cold War-era fears to keep the country weak.

“When we hear constructive criticism, we always listen to it. But when the analysis of our internal situation is used in order to try to bring us all back to the times of the Cold War, we will not agree with it,” the foreign minister, Sergei Lavrov, said last month. “Some people are probably not happy that Russia is growing stronger; some people do not find it acceptable that Russia is becoming more independent politically and financially.”

In a press conference yesterday, Mr. Lavrov made no mention of Mr. Bush’s criticisms the night before. The American president’s comments were given little coverage by state-controlled Russian television and most newspapers.

Mr. Rogov said Russians are concerned by what appears to be a growing consensus, both in America and internationally, that Russia should be isolated. He said the peaceful revolutions in Ukraine and Georgia, which saw Western-backed reformers oust pro-Moscow leaders, are widely seen in Russia as orchestrated by America to strip Russia of influence.

“With regard to Russia, practically everyone is in agreement that an authoritarian regime is being installed here and that Russia is pursuing a neoimperialist policy,” he said. “The thesis of containment has emerged again, for the first time in 15 years people are saying ‘It’s time to contain Russia and fence it off. To take away Ukraine, Georgia, and so on.’ “

Mr. Rogov, of the U.S.A. and Canada Institute, said Russians are increasingly frustrated with what they see as a world turning against them. Even the architect of the collapse of the Soviet Union, Mikhail Gorbachev, has recently taken to accusing the West of interfering too much in Russia’s domestic affairs.

In an interview published Monday, Mr. Gorbachev said: “Let the United States and Europe mind their own business on their own land and we’ll mind our business on our land.”