Ohio Attorney General Mike DeWine (R) will drop his endorsement of Mitt Romney on Friday and back Rick Santorum.
DeWine will endorse the former Pennsylvania senator at a campaign event scheduled for 2 p.m. in Columbus, Ohio, sources confirmed to The Hill. The attorney general and former U.S. senator endorsed Romney in October.
The defection is a coup for Santorum, who has jumped to the front of the GOP pack in polls.
In response, the Romney campaign has pivoted its attacks to Santorum. The two campaigns have been trading barbs in Michigan, where Romney grew up and his father served as a popular GOP governor. Romney won the state by 9 points in the 2008 Republican primary, and Santorum has recently been polling ahead there.