With a close win in Ohio and other victories in Virginia, Massachusetts, Vermont, and Idaho, he remains at the front of the pack.
1:06 a.m. That's all, folks. With only Alaska left to report, we're signing off for the night. Read Molly Ball's analysis of all tonight's results here: A Super Tuesday Nailbiter Puts Romney on His Heels.
Check back in the morning for more analysis from The Atlantic's politics team. --DG
12:44 a.m. Joe the Plumber wins.
COLUMBUS, Ohio (AP) - Ohio's 'Joe the Plumber' of 2008 campaign fame wins GOP nomination in US House race #2012— Phil Elliott (@Philip_Elliott) March 7, 2012
He'll face Democratic Rep. Marcy Kaptur in the general election. --DG
12:31 a.m. Romney wins Ohio. Well, there it is, folks: NBC and the Associated Press have both declared Mitt Romney the winner of the Ohio primary. It's the culmination of a stomach-churning evening: early exit polls showed Romney polling strongly, but as the actual votes came in Santorum gained a significant lead, only to see it melt away as votes from the Cleveland and Columbus metropolitan areas -- which tend to be more socially liberal, better educated, and wealthier -- came in to give Romney a victory. It's unquestionably good news for Romney, who proved he can win in the Rust Belt, and bad news for Santorum, who was unable to hold on to a lead in a state very similar to his own Pennsylvania. A win would have given him serious momentum to keep challenging Romney, though he's vowing to stay on. Still the news could have been much better for Romney, he's escaped with his life, but will have face continued doubts over his inability to finish his rivals -- even though his delegate total by the end of the night puts him well on the way to winning the Republican nomination. Even with the close margin of victory, the former Massachusetts governor will take home the lion's share of the Buckeye State's delegates. --DG