Iron, Richardson has a few problems if he gets the nomination or the VP slot. He has been accused of exaggerating things from his past. Until recently he claimed he was drafted by the Kansas City A's. Unfortunately for him, somebody checked and he was never drafted by any team.
Of much more importance are claims that border on sexual harrassment.
http://www.politico.com/news/stories/0307/3054.html
New Mexico's female Lt. Gov. said she doesn't like sitting next to Richardson. Money quote: "The governor pinches my neck. He touches my hip, my thigh, sort of the side of my leg." As far as I know these issues haven't been a problem yet, but if Richardson ascends in the polls, they will probably become news.