George Will also compared what Reid's doing to Mitt Romney with McCarthyism. My guess is they have no idea what's in his tax returns, that Reid is lying. But they're hoping that data mining 23 years of returns will create a target rich environment, or that they'll be able to make a big deal out of whatever they found. As Ann Coulter wrote recently; President Obama has used sensitive documents to remove competition in just about every election he's ever run. There are no juicy divorce records, there is nothing else. That's why they want these tax records and want them badly.
Feeling Romney wasn't going to cave, Reid apparently became the pick to simply make something up and dare Romney to prove it's false. I thought Preibus' response here was very, very good.