But overshadowing them all may be the evening's emcee: Sen. Hillary Rodham Clinton of New York.
Forget her adamant insistence she has no plans to run for president (at least not in 2004). Never mind that she is supposed to have just a small speaking role at the bash, introducing the candidates after opening remarks. The mere fact Clinton is here, standing literally at center stage in the Democratic nomination contest, is enough to spawn a swirl of speculation.
And that irritates some Democrats to no end.
"It's awful," said a strategist for one of the presidential hopefuls set to speak. "It detracts from the candidates."
A consultant for another of the Democratic candidates agreed. "With a speech like this comes a lot of visibility," said the strategist, who, like others, did not want to be identified criticizing the senator. "We're not only sharing the stage with [all the other] candidates, we're sharing the stage with her as well."
But Clinton brushed aside concerns she might eclipse the other Democrats. "I think this is a terrific opportunity for the candidates themselves to deliver their message to a much broader population than they've been doing," she said Friday from her office in Washington, noting the attention the dinner has drawn.
Stressing that her Iowa visit came at the behest of the state party, Clinton said her appearance "fits into what I've done for years, which is to help support Democratic candidates who are running for office at the state, local and federal levels."
Gordon Fischer, chairman of the Iowa Democratic Party and the one who extended the invitation to Clinton, insisted she was more an asset than a distraction. "To be perfectly blunt," he said, "when we inquired whether she'd be available to emcee, we made absolutely sure there wasn't even a ghost of a chance she was going to run for president."
Still, the circumstances and the setting of tonight's appearance -- about two months before Iowa's caucuses kick off the 2004 balloting -- have proved too irresistible to ignore, for Clinton lovers and haters alike.
Since her election to the Senate in 2000, the former first lady has emerged as one of the Democratic Party's most prolific fund-raisers and biggest stars, despite having kept a relatively low profile on Capitol Hill. Lagging ticket sales took off when she agreed to attend the Des Moines Jefferson-Jackson Dinner, which is expected to draw a record crowd of 7,500. Proceeds will help pay for the state's Jan. 19 presidential caucuses.
But Fischer is not the only one pleased to snag Clinton, who receives 150 invitations each weekday, according to her Senate staff. The senator's Iowa visit -- which includes a Sunday book-signing appearance and separate fund-raisers for a local congressman and her 2006 reelection bid -- also cheers Republicans.
It is not just the prospect of diminishing the Democratic presidential field with her outsize presence. For all her pull as a Democratic draw, Clinton also works fund-raising magic for Republicans. She has replaced the durable Sen. Edward M. Kennedy of Massachusetts as the scary star of direct-mail solicitations, and some Republicans are just as eager as Clinton fans to propagate Hillary-for-president rumors to boost party fund-raising and unsettle the Democratic hopefuls.
"Every appearance she makes with them highlights the weakness of the field," said Christine Iverson, a national Republican Party spokeswoman.
Clinton, whose public appeal fell and rose as first lady with the failure of her ambitious health-care reform plan and, later, her husband's impeachment, is still a polarizing figure. A USA Today/CNN/Gallup poll in June found that 43% of Americans surveyed had a favorable opinion of the senator, while 43% viewed her unfavorably.
Polls aside, she continues to fascinate like few other political figures. Her autobiography became an international bestseller -- more than recouping its $8-million advance -- and has turned into a highly lucrative fund-raising device. (Campaign events have been piggybacked onto Clinton's national book tour.) Recently, the Times of London ventured that she might soon emulate Gov.-elect Arnold Schwarzenegger and become "the next household name to rock American politics."
"The stage is set for a flash of lights, a puff of smoke and the entrance of the party's heroine to sweep all before her," the Times wrote.
Clinton seems alternately annoyed and amused by the continued guessing about whether she really, really, really means it when she rules out a 2004 presidential run. She has cut short interviews when the subject turned to national politics.
But on Friday she just laughed at the theory some posit that presidential hopeful Wesley K. Clark, the retired Army general and an Arkansan, was running as a placeholder for an eventual Clinton candidacy. "Absurd on its face," she scoffed. Clark "is running on his own terms."
Still, for all the protestations, Clinton and her husband have occasionally fueled speculation with remarks like those at a New York fund-raiser in September.
Former President Clinton touted his wife as well as Clark as the "two stars" of the national Democratic Party. He also suggested, "There might be another candidate or two jumping into" the presidential race. Clark did, a few days later.
For her part, Sen. Clinton said the evening's proceeds would be helpful "for my next campaign, whatever that may be." Just kidding, she said later.
The senator is stepping out at a time when many Democrats seem to be veering from the policies pushed by her husband, who favored expanded trade, an assertive foreign policy and a more centrist approach to taxes and social issues.
But Clinton declined Friday to discuss any differences she may have with the party's presidential hopefuls. "I'm not going to second-guess any of the campaigns the Democrats are running," she said. "I think the goal should be to defeat George Bush."
In griping about Clinton's Iowa visit, a strategist for one Democrat running suggested a way she could better serve the party's candidates. "If she really wanted to put an end to all this speculation ... she could say, 'I'm not running for president in 2008 because we're going to elect a Democratic president in 2004,' " the strategist said.
"I've said that many times," Clinton responded. "I've said on many occasions I hope I'll be working for the second term of a Democratic president."