This is provocative: Bill Clinton has endorsed Andrew Romanoff in Colorado's Democratic Senate primary. He's done so despite Barack Obama's endorsement of Romanoff's Democratic opponent (and the incumbent senator) Michael Bennet*. Clinton's rationale seems to be tied to Romanoff's support of Hillary Clinton in the Democratic presidential primary. Ordinarily, that would be fine. But endorsing the challenger after the sitting president has endorsed the incumbent is a pretty big deal--if it's not quite a rebuke of Obama, it's certainly a move that will raise eyebrows. It's fairly well known in Democratic circles that there is no love lost between Bill Clinton and Barack Obama, despite Hillary Clinton's success as Obama's secretary of state. Bill Clinton must have known that his endorsement would stir up questions about his relationship with Obama--and he went ahead and gave it anyway.
*Sen. Bennet is the brother of The Atlantic's editor, James Bennet