“I was wrong,” A.G. DeWine said, as Mr. Santorum stood next to him smiling and, at times, closing his eyes in what appeared to be either beatific reflection or exhaustion.
When A.G. DeWine finished his remarks, Mr. Santorum hugged him, kissed his wife, and spoke briefly, saying he knew how difficult it was for DeWine to switch support.
Polls have shown Mr. Santorum overtaking Mr. Romney in Ohio, a key state both in the March 6 Super Tuesday primary and in the November general election.
A.G. DeWine was elected attorney general of Ohio in 2010. His endorsement is significant, if only because it reflects momentum shifting from Mr. Romney to Mr. Santorum.