The tone yesterday in Pennsylvania, the long-awaited next stop in the Democratic primary march, was lighthearted: For April Fools' Day, Hillary Clinton jokingly challenged Barack Obama to a winner-take-all bowling match for the nomination, then compared herself to Rocky Balboa ("I never quit," she said at an AFL-CIO event). But contrary to all that, the competition in Pennsylvania is actually getting a lot more serious. Recent polls show Clinton's lead there narrowing, and with three weeks left, what once looked like a Clinton landslide could soon become a real battle. Is this yet another sign that Clinton is finished?

• Mark Halperin lists fifteen things Clinton has to do to really "win" Pennsylvania. The most important: dominate the white, working-class voters to prove to the superdelegates that Reverend Wright has hurt Obama. [Page/Time]

• Jay Newton-Small says Obama's Pennsylvania strategy is completely unconventional, for both his decision to campaign in Clinton working-class strongholds and hold quirky events involving bowling, visiting a chocolate factory, and feeding milk to a baby cow. [Time]

• Ariel Alexovich looks at the Jewish vote in Pennsylvania. Clinton has the endorsement of the two biggest Jewish politicians, but 70 Jewish leaders recently signed an open letter in support of Obama. [Caucus/NYT]

• Perry Bacon Jr. and Shailagh Murray note that while stumping in Pennsylvania, Clinton has criticized Obama for wanting her to drop out, while in fact Obama has said she should keep running if she wants. Obama's new tone is an intentional effort to avoid appearing like a bully to — yep — blue-collar Democrats. [Trail/WP]

• Timothy McNulty explores the white male vote in Pennsylvania, which has often gone to Obama in other states but is leaning toward Clinton owing to the issues of race and experience. [Pittsburgh Post-Gazette]

• Carrie Budoff Brown looks at Pennsylvania's struggle to ditch the increasingly inaccurate characterization given to it by James Carville more than twenty years ago, which is, approximately, "Philadelphia and Pittsburgh with Alabama in between." [Politico]

• Bill Barol finds five tongue-in-cheek similarities between Clinton and Rocky Balboa. Number three: Rocky faced off against the Russian Ivan Drago, while Clinton faced off against an 8-year-old Bosnian girl who read her poetry. [HuffPo]

• Maggie Haberman points out a big problem with Clinton's Rocky metaphor: Rocky lost. The paper also runs its own Clinton-Rocky comparison. [NYP]

• Ryan J. Davis believes that Clinton is like Rocky, but more like the Rocky from the fourth sequel, when he became an increasingly irrelevant and desperate old fighter. [Hill] —Dan Amira

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For a complete and regularly updated guide to presidential candidates Hillary Clinton, Barack Obama, and John McCain — from First Love to Most Embarrassing Gaffe — read the 2008 Electopedia.