Tim Johnson of South Dakota was the lone Democratic senator from a conservative state facing reelection in 2014 not to sign a bipartisan letter calling on President Obama to green-light the Keystone XL pipeline. It’s a signal that, combined with recent statements, he’s less attuned to his own reelection and may be considering retirement.Johnson is one of seven Democratic senators from a state Mitt Romney won in 2012, a factor that makes him politically vulnerable. One of the group, Jay Rockefeller of West Virginia, has already announced his retirement after recently taking ... Read More