Obama and Edwards are competing to be the strongest "anti-Clinton" candidate in the field. Both are promising to bring fundamental change to Washington.

Edwards' base of support lies with caucusgoers who were with him when he ran for president in 2004. Obama and Clinton are competing for newcomers — hers are mostly older and female, his are younger and male.

Spending by outside groups has added a new dimension to the contest. EMILY'S List, AFSCME and the American Federation of Teachers are coordinating to boost Clinton through mail, TV and phone banks, while Edwards is receiving assistance from labor-backed groups headed by his 2004 campaign manager.

Obama has called on Edwards to ask the groups to cease their work in Iowa, and privately Obama's advisers fret that he is being hurt by the influx of spending on the other candidates' behalf.

New Hampshire: Jan. 8

The candidates are reinforcing their organizations in New Hampshire, with its 22 delegates, to prepare for whatever verdict Iowa delivers.

The Clinton campaign, which had long counted on the state to be its firewall in the event of a less-than-stellar Iowa showing, has scrambled as her lead here has all but evaporated. The situation was further roiled when a prominent New Hampshire supporter, Bill Shaheen, stepped down as a campaign co-chairman after raising concerns about Obama's teenage drug use.

But Clinton has strong ties to the state thanks to her husband's 1992 and 1996 campaigns. Her organization numbers several hundred staff and volunteers in New Hampshire, methodically working phones and canvassing.

Obama strategists say the key to victory in the state lies with independents who can vote in either the Democratic or Republican primary and who polls show strongly oppose the Iraq war. The campaign is counting on a strong showing among these voters but is targeting traditional Democrats as well, making about 20,000 calls a night.

The Edwards campaign says it has four times the staff in New Hampshire that he had in 2004, when he finished a disappointing fourth. The campaign says its volunteers have knocked on 235,000 doors in the state, where 220,000 people voted in the primary four years ago.

Michigan: Jan. 15

The Democratic candidates have agreed not to compete in Michigan because the state moved the date of its primary in violation of party rules. The Democratic National Committee has penalized the state by stripping all its 128 pledged delegates, but the eventual nominee may choose to restore the delegates prior to the convention next August.

Nevada: Jan. 19