In Colorado last night, Andrew Romanoff lost, Sen. Michael Bennet survived, and President Obama once again irked the “professional Left.” Romanoff, with support from the progressive activists and Bill Clinton, was unable to topple Bennet, the Obama-backed incumbent, in the Democratic Senate primary. Obama, of course, remains toxic for Democrats in general elections (see Massachusetts, New Jersey, and Virginia), but his primary punch is strengthened by the outcome. Unlike Sen. Arlen Specter in Pennsylvania, Bennet was able to overcome Team Obama’s clumsy job offers — the White House allegedly tried to woo Romanoff out of the race with an administration gig — as well as the Beltway stench. With Obama’s help, he swatted and maimed a dashing young lefty. For the president, it’s a Pyrrhic victory: He flexed his political muscle, but in the process, he bruised his core, left-wing base — the base Democrats need to show up this fall. Indeed, for Bennet, the celebration may be short-lived. Like Sen. Blanche Lincoln of Arkansas, who fended off a similar primary challenge, he faces a tough race in November.