WASHINGTON — Senator McCain is seizing on the expanding war in the Caucasus as an opportunity to refocus the presidential campaign on foreign policy and dominate the political spotlight during a week in which his opponent, Senator Obama, is vacationing in Hawaii.

The presumptive Republican nominee yesterday condemned Moscow for the third time in four days and called for a more robust response from the world community to isolate Russia and protect its battered neighbor, a former Soviet republic and an American ally.

As Russian forces advanced deeper into Georgian territory, Mr. McCain said the assault signaled that the Kremlin aimed not simply to oust Georgia from the disputed separatist regions of South Ossetia and Abkhazia but to topple the nation’s elected government.

“This should be unacceptable to all the democratic countries of the world, and should draw us together in universal condemnation of Russian aggression,” Mr. McCain said in a televised statement yesterday morning from Erie, Pa., where he spent the day campaigning. “Russian President Medvedev and Prime Minister Putin must understand the severe, long-term negative consequences that their government’s actions will have for Russia’s relationship with the U.S. and Europe.”

Mr. McCain said America and its allies should push for a U.N. Security Council resolution condemning Russia’s actions, even if it meets with an all-but-inevitable Russian veto. He also urged that the North Atlantic Treaty Organization convene an emergency session to consider an international peacekeeping force and revisit Georgia’s request to become a NATO member.

The Arizona senator called on the Bush administration to send immediate economic and humanitarian aid to Georgia and to work with allies in the region to secure the Baku-Tbilisi-Ceyhan oil pipeline that runs through the country.

Mr. McCain and his advisers clearly see the international crisis as a chance to highlight his foreign policy credentials while his opponent is off the campaign trail.

Mr. Obama issued a lengthy statement hours after Mr. McCain yesterday, and although it was also his third since the crisis erupted last week, the words largely reiterated his earlier criticism of Russia’s military advance and his call for a cease-fire. “No matter how this conflict started, Russia has escalated it well beyond the dispute over South Ossetia and invaded another country,” the Illinois senator said. “Russia has escalated its military campaign through strategic bombing and the movement of its ground forces into the heart of Georgia. There is no possible justification for these attacks.”

He pushed for an international peacekeeping force along with economic and humanitarian aid to Georgia. Yet although Mr. Obama condemned Russia’s response, his rhetoric toward Moscow was far less confrontational than that used by Mr. McCain, who has already pushed for ousting Russia from the Group of Eight industrialized nations.

“Let me be clear: We seek a future of cooperative engagement with the Russian government, and friendship with the Russian people,” Mr. Obama said. “We want Russia to play its rightful role as a great nation — but with that role comes the responsibility to act as a force for progress in this new century, not regression to the conflicts of the past.”

The dean of Baruch College’s School of Public Affairs, David Birdsell, said Mr. McCain’s assertive response to the conflict played to his advantage. “It’s clearly in McCain’s interests to draw as many contrasts as possible with Obama on foreign policy,” he said. “The more anxious people feel about foreign policy, the more it benefits John McCain.”

But Mr. Birdsell said the impact could be limited both by the timing — in the middle of the summer, when many voters are on vacation or watching the Olympics — as well as by the relatively unfamiliar location of the crisis. When most Americans think of Georgia, he said, “they think of the peach tree state.”

He added that Mr. McCain also had to be careful in his language on Russia to avoid sounding militaristic to a war-weary public. “This is plainly an opportunity for McCain, but it’s easy for him to overplay his hand,” he said.