Recent polling reveals a predictable partisan reaction to Sarah Palin as the GOP vice presidential nominee – Republicans swooned, Democrats were less impressed, with “independents” somewhere in between. Sharp political divisions among self-identified partisans are not surprising. But a closer look at the numbers reveals why McCain’s vice presidential selection may gives him a advantage in an election that increasingly looks like it could go down to the wire. From one perspective, the Palin and Biden choices produced similar political consequences. For example, the above referenced ABC poll shows Republicans rating Palin favorably and Democrats rating Biden favorably, with each candidate receiving nearly identical ratings from independents. But Palin’s “favorables” among Republicans are higher than Biden’s among the Democrats (85 percent versus 77 percent). This suggests the Alaska governor helps McCain more than Biden does Obama among each candidate’s respective base voters. The ABC News analysis supports this point: