Sestak to announce challenge against Specter

U.S. Rep. Joe Sestak is set to announce one of the worst-kept secrets in politics tomorrow: a Democratic primary challenge to veteran Sen. Arlen Specter in 2010.

Sestak, a retired Navy flag officer, will make a "major campaign announcement" in an 8:30 a.m. appearance before supporters at the Herbert W. Best VFW Post in Folsom, Delaware County.

That will be followed by a two-day tour that will take him to Pittsburgh, Johnstown, Harrisburg, and Scranton before ending Wednesday with an appearance on Comedy Central's Colbert Report.

Sources familiar with Sestak's plans confirmed it is an announcement tour.

Specter, after four decades as a Republican, 28 of them in the U.S. Senate, switched parties in April because, he said at the time, his party had become too conservative for him to win reelection to a sixth term.

Sestak began criticizing Democratic leaders - including President Obama and Gov. Rendell - for anointing the convert as their preferred choice for the party's nomination. He has all but announced since then, traveling the state and stepping up his attacks on Specter's record.