A clean sweep of the seven states holding primaries or caucuses today could help Massachusetts Senator John Kerry seal his position as the candidate to challenge George W. Bush in November's presidential election.
Today's contests in Arizona, Delaware, Missouri, New Mexico, North Dakota, Oklahoma and South Carolina could reduce the field of major contenders to just two.
Polls show Mr Kerry with solid leads in Missouri, Arizona, New Mexico, Delaware and North Dakota - and within reach of victory in South Carolina and Oklahoma.
But the two Southerners in the race for the Democratic nomination - Senator John Edwards and retired army general Mr Wesley Clark - are hoping they can halt his march.
Mr Edwards is counting on victory in his home state of South Carolina, and Mr Clark is hoping his neighbour state, Oklahoma, delivers. However, in both instances it is the northerner, Mr Kerry who is pushing hard in second.
Western states appear on the horizon for the first time as well, with the Southern candidates expecting a good showing. Mr Clark, in particular, could be in trouble if he shows poorly in Arizona and New Mexico.
One-time front-runner Mr Howard Dean - aiming to put his campaign back on track - is looking beyond today's contests where he has invested little in terms of time or money. He hopes to hit the comeback trail after his disasters in Iowa and New Hampshire when Michigan votes on Saturday.
AP