Why is that you ask? One reason given was the rise of the Religious Right!
"In the 1990s, it really sunk in on the American public generally that there was a long-lasting 'religious right' connected to a political party, and that turned a lot of people the other way," he said of the link between the Republican Party and groups such as the Moral Majority and Focus on the Family...The survey polled 54,461 Americans between February and November of last year.
So to all my politically motivated Christian friends - drop it! You may be doing more harm than good.