Perhaps the most glaring weakness in Rick Santorum’s case that he can win the presidency is his 18-point loss when he sought a third term as senator from Pennsylvania in 2006. Santorum explains that ’06 was a terrible year for Republicans, and indeed the GOP, in the sixth year of George W. Bush’s time in the White House, did lose control of both House and Senate. But why, specifically, did Santorum lose, and why did he lose by such a large margin?

Surprisingly, given the intensity of the campaign, the reasons are seldom explored at any length.  That might be because they cut both ways.  Santorum lost in part for embracing policies that rival Mitt Romney also embraced at the time; citing those reasons today wouldn’t help Romney attack Santorum.  But Santorum also lost in part for entirely personal reasons, alienating many Pennsylvania voters with his temperament and approach to governing; citing those reasons wouldn’t help Santorum defend himself.  So the question has gone largely unanswered.