Name: Joe Sestak
Age: 58
Home: Delaware County
Experience: Congressman and former Navy admiral
Website: http://joesestak.com/Home/Home.html

Rep. Joe Sestak is risking his brief, bright political career bucking the state’s longest serving senator as well as the leadership of his own party.  Mr. Sestak, a retired U.S. Navy admiral, is trying to wrest the Democratic nomination from Mr. Specter, arguing that the incumbent is an ideological question mark.  True Democrats, he contends, can’t count on Mr. Specter’s vote any more than Republicans could.  Mr. Sestak has portrayed himself as the outsider’s candidate, hoping to capitalize on the anti-incumbent sentiment of recession-battered voters.

He captured his suburban Philadelphia House seat in 2006, ousting a veteran Republican.  Early polls haven’t shown him making much headway against Mr. Specter.  But that could change fast.  Mr. Sestak is sitting on more than $5 million in campaign cash, meaning that he has the resources to raise his name ID quickly as the primary enters its home stretch. On one tactical level, this race will be a referendum on the incumbent.  But another component of the competition will be a race to define Joe Sestak to voters who hardly know him.

Name: Arlen Specter
Age: 80
Home: Philadelphia
Experience: Five-term senator and former prosecutor
Website: http://www.specter2010.com

Arlen Specter, the state’s longest serving senator, the great survivor of Pennsylvania politics, may face his toughest test this year.  His stunning shift from Republican to Democrat last April gave his new party a temporary filibuster proof majority in the Senate.  But his switch was rewarded with an energetic challenge in the primary of his new party, from Rep. Joe Sestak, a retired admiral from Delaware County..  If he survives that, he will face a familiar opponent in November -- former Rep. Pat Toomey, the conservative Republican who nearly ousted him in the GOP’s 2004 primary.

To survive once again, Mr. Specter is relying on the strengths of incumbency and his decades of cultivating support with regular visits in each of the state’s 67 counties.  Mr. Specter also has the support of the Democratic hierarchy including President Obama, Vice President Biden and Gov. Ed Rendell, his former aide in the Philadelphia district attorney’s office.