PewResearch:

Two-thirds of Americans (67%) say there is solid evidence that the earth has been getting warmer over the last few decades, a figure that has changed little in the past few years. While partisan differences over climate change remain substantial, Republicans face greater internal divisions over this issue than do Democrats.
That number, however, drops to 44 percent if the warming is attributed to humans, and down to 9 percent if the person asked about human attribution happens to be in the Tea Party.