One Republican argument about Sarah Palin is that the Alaska governor has proven willing to challenge her party in a way Barack Obama has not. Rebutting that charge should be easy. But it also represents something of a trap for the Democratic nominee.
A glance at the last year, of course, shows that the idea of Obama cowering before the party establishment is hooey. He's the nominee precisely because he challenged, against what at the time seemed like very long odds, the biggest name in the national Democratic Party, a Senator who began the race with the bulk of the party establishment firmly in her camp. The safe move would have been to wait for his shot. Obama declined to do so. In the process, he did more or less what Palin did in Alaska when she challenged a sitting GOP governor who had previously logged decades in the Senate and become one of the state's political titans.
The problem for Obama, what with the lingering anxiety over Hillary voters and the promises of chumminess after Denver, is that it's quite hard to point this out. Boasting about being a giant killer, and implicitly comparing Hillary Clinton to Frank Murkowski, is no way to win over her supporters. Not doing so, though, denies Obama a chance to show off something it's easy to forget now that he's won--the bravery it required to take on the Clintonian establishment. It also keeps him from showing off, in the general election, his hard-earned status as one of the most appealing things in politics: A winner.