Conor O'Clery
in New York
The battle for the Iowa caucus next Monday, the first contest in the race for the Democratic presidential nomination, has come down to a struggle between anti-war front-runner Mr Howard Dean and pro-union Congressman Mr Dick Gephardt.
The latest poll shows Mr Dean leading Mr Gephardt by 30 points to 23, with Senator John Kerry trailing on 18 points, and Senator John Edwards at 11.
Mr Dean received the endorsement on Friday night of popular Iowa senator Mr Tom Harkin, just as his campaign was losing support over comments he made four years ago about the caucus being "dominated by special interests".
Former vice-president Mr Al Gore also came to Iowa to support Mr Dean, making his first campaign speeches since running for president in 2000.
House Democratic leader Ms Nancy Pelosi of California campaigned for Mr Gephardt, while Senator Edward Kerry turned up in the snowy mid-western state to support Senator Kerry.
Iowa is facing its most competitive Democratic caucus in 16 years, and the outcome is uncertain .
According to a Los Angeles Times poll, some four in 10 Iowa Democrats have not yet made up their minds on how to vote.
Mr Gephardt, who has been drawing more enthusiastic crowds than earlier, accused Mr Dean of being "all over the lot" on Iraq and on Medicare.
"I just don't think we can beat George Bush if you've got many, many different positions on important issues," he said.
On the CBS Face the Nation programme, Mr Gephardt said the race was "a dead heat between Howard Dean and me".
"And I think when voters really bear down on this, which they'll do in the next week, and look at who has the best ideas . . . who has steady hands, experience, doesn't make mistaken statements every day that have to be clarified the next day, I think people are going to settle on me."
Addressing undecided voters, Senator Harkin said: "This is the person, Howard Dean, who is electable, who has the toughness, the courage of his convictions, plain-spoken, who is not afraid to take a stand."
Recalling how Iowa voted for his brothers Jack and Robert Kennedy, Senator Edward Kennedy asked a rally of 600 electors: "Are you going to do it for John Kerry?" As the main critic of the war in Congress, Senator Kennedy could sway some Democrats who oppose Mr Kerry because of his support for a Congressional resolution authorising war against Iraq.
In New Hampshire, where the first primary takes place on January 27th, retired general Mr Wesley Clark, who has opted out of the Iowa caucus, has moved into second place behind Mr Dean.