Michigan Primary: "Pivotal State."

The ballot for Michigan's January 15 presidential primary is officially settled,as of Friday afternoon--setting the stage for a key battle for the Republican nomination.

Democratic candidates Barack Obama and John Edwards had both removed themselves from contention in the Michigan primary late last year--leaving U.S. Senator Hillary Rodham Clinton as the only major candidate in the state's Democratic contest.

However, after strong finishes by Obama and Edwards in Iowa, political insiders speculated that their campaigns might petition the Michigan Secretary of State to add themselves as write-in candidates.

Neither candidate filed by the 4 p.m. Friday deadline. Kelly Chesney, a spokesperson for the Michigan Secretary of State's office, said Friday that neither candidate's write-in vote would be counted on January 15.

Meanwhile, Republican voters have a full choice of candidates: All of the top candidates, including Mike Huckabee, Mitt Romney and John McCain, are on the ballot.

Most analysts consider Michigan's primary a key contest among Republicans.

"This is going to be a pivotal state in the Republican nomination process," said Steve Mitchell, president of West Bloomfield-based Mitchell Research and Communications.

"If Huckabee wins Iowa, and Romney or McCain win in New Hampshire, that means Michigan is critical to all of the candidates," said Mitchell.

Huckabee beat Romney by nine points in Thursday's Iowa caucuses, making New Hampshire critical for Romney.

The former Massachusetts governor also may need to win his native state of Michigan to remain viable, especially if he doesn't win New Hampshire.

Associated Press contributed to this story.