And while Mr. Toomey rightly expresses concern about the growing national debt, he seems to think it is solely the result of decisions by President Barack Obama, with help from Mr. Sestak and other congressional Democrats. He contended that earlier decisions slashing taxes while conducting two hugely expensive wars constituted sound policy, for example. Mr. Toomey is not, like former Sen. Rick Santorum, an ideological flamethrower. Yet on policy matters he probably is even more conservative than Mr. Santorum and most other current members of Congress. Mr. Sestak's views are shaped by his military career, during which he rose to...