DAVENPORT, Iowa — Senator Biden, a Democratic presidential candidate who is behind in polls and campaign money, is betting the farm on Iowa’s leadoff caucuses, hoping a strong showing will rocket him to the top of the field. If not, Mr. Biden admits he’ll be an early footnote in the race for his party’s nomination.

“I’m counting on Iowa a lot,” Mr. Biden said in an interview with the Associated Press. “My expectation is that I come in first, second, or an indistinguishable third. To tell you the truth, if I don’t, then this has been a nice exercise, and I’ll see you again when you come to visit Washington.”

Mr. Biden, 64, brings a blue-chip resume to his second bid for the Democratic presidential nomination. He’s represented Delaware in the Senate since 1972, and as chairman of the Senate Foreign Relations Committee, he’s in the middle of the debate over the Iraq war. Most polls show that’s the top issue with voters, and Mr. Biden has been an early and persistent critic of Mr. Bush’s policy — a strong selling point with overwhelmingly anti-war Democratic activists.

Still, Mr. Biden is at the back of the pack in polls nationally and in Iowa.

In response, he’s campaigned in the state for much of August, spent heavily on television commercials highlighting his stance on Iraq, and announced plans to expand his Iowa staff.

“We’re gaining some traction here,” Mr. Biden said. “We’re bringing the real first team.”

That support has yet to be reflected in any polling, and in the interview, Mr. Biden acknowledged the hurdles he faces. But he said he senses an opening that could vault him past the current front-runners.

“At the end of the day, I’m a tactile politician, and I trust my feel, and I’m telling you I think there’s some pace on the ball,” Mr. Biden said. “I’m not trying to make this a groundswell, but there’s something there that’s genuine.”

Others aren’t convinced.

University of Iowa political science professor Bruce Gronbeck said Mr. Biden has a habit of talking his way into trouble.

“I don’t think he’s showing much traction,” Mr. Gronbeck said. “There’s a sense he’s something of a loose cannon.”

Drake University political science professor Dennis Goldford said Mr. Biden can’t keep his head out of Washington, often burying voters with arcane detail.

“He talks like a senator, not a president,” Mr. Goldford said. “The forest gets lost in the trees.” Even those more optimistic about Mr. Biden’s chances said he must convince Iowans that he could be a top finisher. Few caucus-goers want to venture out on a winter night to support an also-ran.

Democratic strategist Ron Parker said Mr. Biden has convinced voters he’s qualified, but now must assure them he can win.

“He’s got to demonstrate he’s in the top tier, or otherwise he’s in big trouble,” Mr. Parker said.

Mr. Biden says he has reasons for optimism, arguing that most Iowans haven’t made up their minds despite the enormous press attention given to Senators Clinton and Obama.

“I look at the rest of the field and I say, ‘God, I’d love to have their money,’ mainly to have their plane because it makes life a lot easier,” Mr. Biden said. But there are limits to how far a giant stash of money can get a candidate in Iowa, where television ads typically rank second to personal campaigning.

“I don’t need $100 million to compete in Iowa,” Mr. Biden said. “My observation over time is you Iowans are kind of contrarians. You don’t anoint front-runners.” Mr. Biden seems to relish the nonstop campaigning. His schedule can take him through a half-dozen stops a day. He routinely runs late, slapping backs and schmoozing as he makes the sale one voter at a time.

“I’m a pretty good retail campaigner,” he said.

That, he contends, will pay off this fall as the caucuses near and Iowans begin paying closer attention.

Although he’s betting everything on Iowa, Mr. Biden said the movement of large-population states to the start of the nominating process means a poor showing in the lead-off caucuses would be disastrous for any candidate. Without the boost from a top finish in Iowa and New Hampshire, even the front-runners will be in trouble, he said.

That dictates a simple campaign strategy, Mr. Biden said.

“It’s kind of like Iowa, Iowa, Iowa, Iowa,” Mr. Biden said. “New Hampshire, New Hampshire, New Hampshire.”