TOLEDO, Ohio – For months, supporters of Senator Barack Obama have been knocking on doors across the country to rally enthusiasm for his candidacy. On Sunday, he joined them at a few doorsteps.

As Mr. Obama arrived in northern Ohio to begin preparing for his third debate with Senator John McCain later this week, he made a detour to the Lincoln Green neighborhood of Holland for nearly an hour of impromptu door-to-door campaigning.

The locations of Mr. Obama’s debate camp have been built around the politics of battleground geography. For the first debate, he and his circle of advisers converged on Florida. For his next debate, the Obama team hunkered down in North Carolina. And for the final encounter with Mr. McCain, the Obama campaign selected the Toledo area.

His visit on Shrewsbury Street clearly took some residents by surprise, including Sue Sekel, 43, who was cleaning her house when the presidential candidate rang the doorbell.

“The one day I come home to clean ceiling fans and look like crap, and then this happens,” said Ms. Sekel, who pulled out her cell phone to snap a photograph with Mr. Obama. She told him that she had already voted early, but declined to tell a small group of pool reporters who she supported.

But Mr. Obama seemed to give away the secret, saying: “I appreciate that,” before moving to the next house on the block.

As word spread that he was in the neighborhood, a crowd began to gather, nearly all of whom seemed to be excited by the political visit. Before leaving, though, he was confronted by a man, who shouted: “Do you believe in the American Dream?”

When Mr. Obama answered yes, the man said he had a follow-up question.

“I’m being taxed more and more for fulfilling the American Dream,” the man said, perhaps referring to Mr. Obama’s plan to increase taxes for those making $250,000 a year or more . While Mr. Obama ran through a series of points about how his plan would mean tax cuts for 95 percent of people, that didn’t seem to convince the man.

“I’ve got to go prepare for this debate,” Mr. Obama said as he walked away. “But that was pretty good practice.”