Will The Senate Lean Further Left?

Jamelle Bouie thinks it just might. The significance:

If President Obama wins the election, liberals will have a better shot at stopping any “grand bargain” that makes regressive cuts to Social Security and Medicare. And if Romney wins? He’ll have to negotiate with a more liberal Democratic caucus, which means, in effect, that some promises of his campaign — large cuts in spending and taxes — will have to be moderated, or go unfulfilled.