The bigger tests will be New Hampshire, Michigan, South Carolina, and Florida later this month. Whoever is doing well at the end of Jan will be judged viable on Super Tuesday (Feb 5).
Whoever is trailing badly after Feb 5 is finished as a candidate
Edwards & Obama are not on the ballot in Michigan. They refused to campaign when Michigan moved up their primary. They have until 4:00 PM today to register as “write-in” candidates.