Two polls released in the final weekend of campaigning put the Senate majority leader comfortably ahead in Iowa, with 28 per cent against 16 per cent for his closest rival. In one poll this was the publishing magnate Steve Forbes; in the other, the current "hot" candidate, the right-wing commentator Pat Buchanan.
But Lamar Alexander, the former Tennessee governor, is also in double figures, closely followed by Senator Phil Gramm of Texas, despite his humiliating defeat at the hands of Mr Buchanan in last week's Louisiana caucuses.
Adding to the uncertainty is the quarter of likely voters who say they are undecided, and the angry claims of Mr Forbes that his campaign is being undermined by an anonymous phone campaign mounted by the Dole camp.
"They did it in last month's Alaska straw poll, it's happening here, and they're doing it in New Hampshire [where the crucial first primary will be held next Tuesday]," Mr Forbes told supporters here on Saturday evening. Mr Dole denies everything, but a former employee of a Utah telemarketing company claims he made such calls, understood to be on behalf of the Kansas Senator.
The aim, allegedly, has been to blacken Mr Forbes's name among religious conservatives, who may account for half of all Republican caucus-goers tonight.
In fact, the real culprit is the dubious but widely used campaign technique of "push polling", theoretically designed to identify weaknesses of rival candidates but which can easily mutate into smear campaigns by another name.
If so, the tactic seems to be working. By the Forbes camp's own admission, his backing among the so-called "social conservatives" has plummeted, amid doubts over his anti-abortion and anti-gay credentials. Most of that support seems to be going to Mr Dole and Mr Buchanan, with a smaller portion crossing to Mr Gramm.
In a bid to recoup the lost ground, Mr Forbes yesterday added to the $15m (pounds 10m) he has already spent on advertising by running 30-minute promotional "info-mercials" on Iowa television stations, akin to the paid programmes of the billionaire Texan businessman Ross Perot during his 1992 run for the White House.
But the protestations by Mr Forbes are arousing scant sympathy - indeed, they are widely seen as just deserts after the torrent of negative TV advertising he has loosed in a state where gentlemanly town-hall campaigning and cosy chats with candidates is a sacred tradition. The advertising may also have disgusted some Republicans enough to keep them from the caucuses, although Iowa's Republican Governor, Terry Branstad, predicted a record turn-out of 150,000 or more at the 2,142 individual caucuses across this farmbelt state.
Otherwise, though, the campaign is ending much as it begun, bereft of ideas apart from Mr Forbes's flat-tax and Mr Buchanan's "America First" crusade to protect US workers' jobs and dismantle the North American Free Trade Area, and conducted largely in fealty to the Christian right.