Emotion is motivational. Emotions bubble away under the surface even when the stimulus that ignited them has been removed -- or disproved.
For example, economists pretty much agree that the president of the United States doesn't have many levers to lower gas prices. And those he has, have been pulled. This article provides a good summary.
Nevertheless, the Republican presidential candidates seem to believe that, if they can link rising gas prices to the president, his approval will fall and he won't be reelected.
The evidence for that assumption is mixed at best. Obama may not be reelected, but few political scientists think rising gas prices will be the cause.
But count on that trope to be added to others in the GOP quiver, along with "Obama the Food Stamp President" and "when I'm president, I won't bow to a Saudi King."
Incompetence-by-association is easier to pitch than a factual brief.
Democrats have also been known to condemn by association. They've kept Romney's dog on the roof of that car far longer than I thought possible. And whatever Santorum thinks about contraception and pornography, I doubt it will shape major intiaitives in his presidency.
Politics today involve more misdirection than a game of Three Card Monty.