Huff Post's Sam Stein spoke to George McGovern, who had this bit of advice for Obama on choosing his running mate:

"Remember the Hippocratic Oath that doctors take: first do no harm," said the South Dakota Democrat in a telephone interview. "You want to be sure that whoever you pick is not going to prove to be a controversial person and make it more difficult for you to run."

Good advice, especially for a candidate who's had his fair share of "controversial persons" this year. Fortunately for Obama, most of the choices on his short-list have gone through the vetting process.