For some reason, someone decided long ago that politicians with their eye on an elected office should essentially announce that they're running while, for months, saying that they haven't actually announced that they're running and that they still need to check with their third cousin's boyfriend's college roommate before they do.
It's a weird system, but it's the one we have, and it's the one that Rep. Joe Sestak, D-Pa., has been following as he's teased supporters with the prospect that he'll mount a primary challenge to Sen. Arlen Specter, D-Pa.
Now, though, Sestak has decided to end the charade, and he will officially announce -- for real this time -- his campaign on Tuesday.
Sestak is the underdog in the race, especially with the Democratic establishment having pledged its support to Specter. But he does have a shot at victory, and Specter's numbers have been falling generally.