George Mason University's Center for Media and Public Affairs may have come up with a decent reason for why GOP candidate Mitt Romney seems a little shy about going on late-night shows. Since the party conventions, late-night comedians, including Jay Leno, David Letterman, Craig Ferguson and Jimmy Fallon, have told more jokes about Romney than all the Democrats combined. In addition, Republican pols were targeted by jokes more than twice as often than their Democratic counterparts, a study out Wednesday suggests. Here's the joke totals:

148: Jokes told about Mitt Romney

62: Jokes told about President Obama

290: Jokes told about Republicans

138: Jokes told about Democrats