Last night, when Mitt Romney swept five state primaries, he broke a couple of records along the way. They're not records he's going to be boasting about anytime soon, though:

A Smart Politics review of Republican primary election data since 1972 finds that Mitt Romney's performances in Delaware and Pennsylvania mark the first time a GOP frontrunner has failed to reach the 60 percent mark in a contest conducted after his last major challenger dropped out of the race.

That's another glass ceiling shattered, thanks to the Republicans.