With Senator Obama on the other side of the planet, Senator McCain stayed closer to home yesterday, visiting Yankee Stadium with Mayor Giuliani.

The two high-profile Republicans are longtime friends, despite having campaigned against each other in the 2008 Republican primaries in which Mr. McCain, ultimately prevailed. When Giuliani bowed out of the race, he immediately endorsed Mr. McCain.

Could Mr. Giuliani, who moonlights as the no. 1 Yankee fan, become the no. 2 on the Republican ticket?

“You hear all kinds of stuff, but I’m not thinking about anything but helping to get him elected,” Mr. Giuliani said. “Beyond the fact that he’s the candidate of my party, he’s a very good friend.”

Before the game, Mr. McCain, Mr. Giuliani, and Mr. Giuliani’s wife, Judith, went onto the field, chatting with the Yankees manager, Joe Girardi, and the Oakland Athletics manager, Bob Geren.

When Mr. Geren asked Mr. McCain what it’s like to run for president, Mr. McCain answered that it was like being in minor league baseball, “and all of a sudden you’re playing in Yankee Stadium.”

The politicians then walked down the third base line, waving to the fans who showed up early. At first, few seemed to recognize Mr. McCain, instead hollering out “Rudy” in recognition of the former mayor. Mr. McCain visited Monument Park, where plaques honor the Yankee greats, including Babe Ruth.

The former mayor, whose name is also bandied about as a possible candidate for New York governor, said Mr. Obama’s trip abroad highlights the gap in experience between the two candidates. Obama is traveling to Afghanistan, the Middle East, and Europe.

“I think the fact that Barack Obama is kind of making his first tour, in essence, of the world, gives you an indication that John McCain is the man with the experience. John doesn’t have to go for the first or second time to these places. He’s been going for 20, 30 years. He knows the world,” Mr. Giuliani said.

While Mr. Obama is overseas, Mr. McCain has spent a low-key weekend in New York. On Friday night he appeared on Late Night with Conan O’Brien, then spent Saturday in the Hamptons raising campaign money, including at the home of Ron Perelman, a billionaire whose controls Revlon Inc.

Yesterday morning he had a private meeting with Schools Chancellor Joel Klein, whom Mr. McCain has publicly praised for his education reforms. Mr. Klein declined to comment as he entered Mr. McCain’s hotel for the meeting.