DES MOINES, Iowa — As John Edwards barnstormed Iowa during the final hours before the state's presidential caucuses, an army of volunteers continued to push to wrangle votes for him.

Edwards, a Chapel Hill resident and former U.S. senator from North Carolina, was conducting a 36-hour "Marathon for the Middle Class," criss-crossing Iowa to close the deal with undecided voters before they caucus Thursday night in cities and towns statewide to begin the 2008 presidential nomination process. Pop singer John Mellencamp was expected to appear at a Wednesday night concert as part of the get-out-the-vote effort.

Polls indicate Edwards is in a tight race with Illinois Sen. Barack Obama and New York Sen. Hillary Clinton in Iowa, although national polls place Clinton far in front of Obama, with Edwards trailing in third place.

Meanwhile, Gus Gusler of Raleigh was going door to door in snow and freezing temperatures in Ames, Iowa, trying to pick up a vote at a time. Some residents were coy in revealing their favored candidates, he said.

"A lot of these people are really cagey. They just won't tell you whether they're decided, and if they're decided, they won't tell you who (they support). They just smile, and we ask, 'Are we in the top two?'" Gusler said.

A veteran of George McGovern's unsuccessful 1972 presidential campaign, he said he enjoys meeting voters. An Obama supporter invited him to dinner Tuesday for a Southern tradition of black-eyed peas, greens and ham hocks on New Year's Day.

"It's pretty amazing to have this opportunity," Gusler said. "Not that many people get the opportunity in life to go out and do something for somebody you really care about and believe in."

Volunteers from across the country said they passed up holidays with their families to campaign for Edwards in Iowa.

North Carolina Secretary of State Elaine Marshall and Durham attorney Kerry Sutton were joined on the front lines with people from Pennsylvania to Texas to Indiana.

Robin Winston, of Indianapolis, said he wanted to work a phone bank for Edwards in a Des Moines union hall because the candidate hearkens back to former President John F. Kennedy.

"I remember growing up respecting the president of the United States," Winston said. "I want my child – I have an 8-year-old – to grow up in that same environment, where they respect the president, they respect what they're doing and they have a future and an optimism about the federal government and what it can do to make a difference.

"I think, more than anyone else, John Edwards does that," he said.

Campaign volunteer Linda Frankel said Edwards represents a change for the nation.

"He stands for the transformation of the United States and for the world," Frankel said. "This is a new era that's coming when he's president."