After Michigan Democrats refused to disregard their state's planned January 15 primary, four top Democratic candidates have filed papers with the Secretary of State to withdraw their names from the ballot. Sen. Barack Obama, ex-Sen. John Edwards and New Mexico Gov. Bill Richardson said they would take their names off the state's primary ballot today, according to the Detroit Free Press. Sen. Joe Biden sent out a release saying he, too, would take his name off the ballot today, the last day to legally do so.

Michigan is home to Sen. Carl Levin and party activist Debbie Dingell, wife of Rep. John Dingell, the two most active members of a group of Democrats trying to break the stranglehold Iowa and New Hampshire have on the presidential nominating process.

Candidates earlier this year were asked to sign a pledge not to campaign in states that violated the DNC's rule prohibiting nominating contests held before February 5th. Only Iowa, New Hampshire, South Carolina and Nevada are allowed, under DNC rules, to hold early contests.

Other Democratic candidates, including front-running Sen. Hillary Clinton, have yet to issue statements. They have about four hours to make their decisions. The DNC Rules and Bylaws Committee will likely treat Michigan to the same sanctions as Florida, which, by holding a January 29 primary, lost all its delegates to the 2008 convention.

It remains likely that both states' delegates will ultimately be sat at the convention, thanks to the presidential nominee's control over membership on the Credentials Committee. Still, the move is another step towards chaos endemic in this year's primary calendar.

UPDATE: Blake Dvorak has the report that Clinton will stay on the ballot in Michigan. How the first four primary states will react could propel this story for a few more days.