Four Democrats pull out of Michigan presidential primary

LANSING, Mich. (AP) - Barack Obama, John Edwards, Bill Richardson and Joe Biden have withdrawn from Michigan's January 15 Democratic presidential primary.

The candidates filed paperwork to withdraw today, the deadline to withdraw from the ballot, according to the Michigan Secretary of State's office.

All of the Democratic candidates already have agreed not to campaign in Michigan because it broke Democratic National Committee rules when it moved its primary ahead of February 5th.

Other Democratic candidates had until the end of the day to decide if they'll stay on the ballot.

Posted by LS

CBS and Associated Press contributed to this report.