[kabar]

Obama did lose an election. In 2000, he lost a Democratic primary race for Illinois’s 1st congressional district in the United States House of Representatives to four-term incumbent Bobby Rush by a margin of two to one.

[newzjunkey]

Interesting but losing a primary to an entrenched incumbent of your own party doesn't have the same effect as losing in a general.

Romney's loss to Ted Kennedy was probably a good thing as Romney himself noted in the 2012 GOP debates.