Republicans still revere Reagan. Even critics call him the "Great Communicator". His "Morning in America" was brilliant PR. He boosted confidence in a non-specific way that encouraged people to tell themselves, "Things are getting better."
Critics at the time said, "You can't just say things are getting better and that makes them better." Except that if you can effectively change a mood -- with a figurehead speaking reassuringly and a huge political machine dedicated to agreeing with him -- you can help to foster a virtuous cycle.
If, on the other hand, the huge political machine is dedicated to questioning everything the current figurehead says, it seems reasonable to suppose this could foster a negative spiral.
Now is where you say, "Gotchya! You just admitted that uncertainty can depress the economy."
Then I point out that the uncertainty isn't caused by what the figurehead is saying, but how the political machine responds to him. When I said earlier that the Republicans could end the uncertainty immediately by simply agreeing with whatever Obama says, that wasn't facetious.
If you really think uncertainty is the most important factor in continued slow growth, shouldn't you be advocating going along with Obama for the good of the economy?
I'm still not agreeing with your premise that uncertainty is the primary factor at work, just saying that to the extent that it is, it's a problem not of Obama's making.