Salena Zito

Rendell is with Clinton, who is the Casey of this race; she plays to the same demographics -- conservative Catholic Democrats. To hold her lead and win, she must spend time in Southeastern Pennsylvania and try to appeal to its suburban Philadelphia's “soccer moms.”

Obama is 2008’s Rendell -- the media darling, the person who will win Philly’s Democrat machine. Wisely, he plucked Casey from the “I am not going to decide” sidelines and will use him to cut into Clinton’s base.

If the Obama camp really wants to exploit any Casey effect, it should produce Casey ads for the Pittsburgh, Scranton, Erie and Altoona/Johnstown media markets.

Obama can and will do better than Rendell did in South-Central Pennsylvania. If you’re a Democrat in Lancaster (and, by volume, there are a lot of them), you’re a liberal (read: Obama) voter; add up the Democrats in Dauphin, Lancaster, York and Cumberland, and that’s a decent base on which Obama can make up ground.

Just as Rendell did against Casey.

For Clinton, the smart move would be to place Rendell nonstop on television in Harrisburg and Philly.

One unanswered question is, what impact will Philadelphia Mayor Michael Nutter have on this race? If he helps Clinton cut into Obama’s base, then he’ll help her to win big; if not, then he’ll have no relevance.

Right now, he may be more important than Rendell in Philly.

While many Keystone Staters are beside themselves watching a presidential primary battled out here, some are keeping an eye on the other big battle: Casey vs. Rendell.

This primary may finally settle the feud between those two, which, despite the official handshakes and smiles that never reach up to either man’s eyes, remains very real.

Salena Zito

Salena Zito is a political analyst, reporter and columnist.