The fine folks at Pew surveyed the public and members of the Council on Foreign Relations to compare the two across a wide range of topics, from troop surges to national prominence.
The graph to the right (here for a bigger image) shows the American public's view of the U.S. role as a world leader. What people perceive is headed south compared to the previous survey, the lowest point Pew has found since 1974 (though probably within the margin of error, so don't go too far on that last datum).
In a way, you can argue what people know about international affairs is reflecting a bit more of reality. We can argue that point to death, and conservatives would love to argue that Obama is the cause. My own sense is it's a combination of the recession and job losses, a lengthy war without resolution, and finding nearly everything in the Wal-Mart has been made by China.