Jimmy Carter was one of the most outspoken Christians to occupy the White House. He is also a liberal. And his book, Our Endangered Values: America's Moral Crisis, takes more than a few shots at social and political conservatives who also claim to be Christian. Carter's book is one of several reviewed by Christopher D. Levenick for the Claremont Review of Books, a publication of the Claremont Institute.
As Levenick points out, the 2004 election was a wake-up call to the Democratic Party and the Political Left (in general). There is little doubt that the so-called "values voters" pushed George W. Bush to victory. And these "values voters" were dominated by professing, evangelical Christians. Self-proclaimed Christian leaders from the liberal side of the proverbial house have made it their mission to woo some of these "values voters" away from the Republican Party.
Levenick reviews a few such efforts:
http://www.claremont.org/publications/crb/id.1279/article_detail.asp