This a great question, and it highlights a commonly noted - if problematic - reality. People who identify with different political parties look at the world in substantively different ways, and these viewpoints tend to be conditioned by the cues they receive from party leaders. This goes beyond party identification. Ideology and group identification, among other many other criteria that people use to identify themselves can distort how people look at the world.
The following story is the latest in a long line of stories on this subject. The author begins by noting that Democrats and Republicans have shifted their opinions recently on whether presidents have any direct impact on gas prices:
When pollsters ask Republicans and Democrats whether the president
can do anything about high gas prices, the answers reflect the usual
partisan divisions in the country. About two-thirds of Republicans say
the president can do something about high gas prices, and about
two-thirds of Democrats say he can't.
But six years ago, with a Republican president in the White House, the numbers were reversed:
Three-fourths of Democrats said President Bush could do something about
high gas prices, while the majority of Republicans said gas prices were
clearly outside the president's control.
The flipped perceptions on gas prices isn't an aberration, said Dartmouth College political scientist Brendan Nyhan.
On a range of issues, partisans seem partial to their political
loyalties over the facts. When those loyalties demand changing their
views of the facts, he said, partisans seem willing to throw even
consistency overboard.
What is consistent is that identifiers of one party will believe anything that will put the member of the other party in a negative light. If facts get in the way so be it. Andrew Sullivan argues that it might be best to think of loyalty to a party like loyalty to a sports team. Have you ever changed your opinion of a player you once despised because he gets traded to your team? What's with that - he's still the same person, just wears a different uniform.
Now while we may be critical - justly - of this tendency, its instructive to note that this is fact how people behave politically. One of the point hit repeatedly in class is that the framers of the Constitution assumed that the negative aspects of human nature - of which this is an example - could not be readily cured. The constitutional order had to compensate for it. So a good question for us to raise in class is whether the Constitution does so.