If you look at the evidence of the number of safe seats in the House, at increasing percentages of registered Republicans vs. Democrats, or at who controls all three branches of the federal goverment, then you have evidence of the rightward drift.

If you look at the increasing percentage of people who support a woman's right to choose, affirmative action, or civil unions; and you watch the demographic shifts that should lead to more Democratic support, then you may see the opposite.