All seven Republican members of the Senate Judiciary Committee have signed a letter to Attorney General Eric Holder asking him to appoint a special prosecutor to investigate Pennsylvania Senate candidate Joe Sestak’s claim that a mystery someone in the White House offered him a mystery position in the administration if he’d drop out of the primary race against Arlen Specter. Apparently Robert Gibbs’s explanation which was basically, “We looked into the accusations against us, and we’re innocent” wasn’t convincing. For what it’s worth, this type of horse trading is pretty common. [Political Punch/ABC News]