Left Behind: How Democrats Are Losing the Political Center - William Galston

http://www.tnr.com/article/the-vital-center/95296/democrats-ideology-republicans-independents

Compounding the problem, the American people are gradually polarizing. According to Gallup, twenty years ago, as Bill Clinton began his presidential campaign, self-described moderates formed the plurality of the electorate—43 percent; conservatives were 36 percent, liberals 17 percent. By the summer of 2011, the conservative share had risen to 41 percent and liberals to 21 percent, while moderates declined to 36 percent, surrendering their plurality status to conservatives. Because nearly all conservatives now vote for Republicans and liberals for Democrats, the share of the shrinking pool of moderates that Democrats need to build a majority is now larger than ever.