NEW HAMPTON, Iowa, Oct. 5 — A broad grin spread across Senator Barack Obama’s face as he turned to walk away from a city park here on Friday after shaking the last hand and posing for a final photograph with a clutch of supporters.

Given the political news of the week, at least back in Washington, why the smile?

“It’s not over,” Mr. Obama said, pausing for a moment to answer an open-ended question about the state of the campaign. “Presumably if they thought the race was over, they wouldn’t be taking the time to come to a town hall meeting to talk about the presidential race.”

If the chase for the Democratic nomination appears to have reached a stage of inevitability, if Senator Hillary Rodham Clinton of New York is becoming a runaway front-runner as national polls might suggest and some of her rivals are beginning to fear, the word has not reached the voters here in Chickasaw County.

It is not that the 200 or so people who turned out to see Mr. Obama on Friday morning are oblivious to such prognostications. As ardent political enthusiasts, many of them obsessively follow them. But the voters here have not necessarily become believers, particularly before they have a chance to size up the competition when it comes to town.