[WS:] I take your point. But it may as well be argued that they are winning because they are so hysterical. Or perhaps winning enough people to sway elections their way by a slim margin. Another point - how do we know that they are losing? It is not immediately apparent from election results, or union membership, or support of labor, or attitudes toward immigrants, or consumer behavior, or attitude toward public programs and institutions.
Thomas Frank attributed the rather wide spread of pro-business and reactionary views in the mainstream of US society to propaganda, and I found that convincing. One may of course disagree, but then one would need to come up with an alternative explanation. What is it?
However, I fully agree with your argument that factual argument and empirical documentation is the duty of left critique. But that does not mean that this critique should be limited only to such arguments and documentation. Congressional liberals are often criticized for limiting their discourse to dry technical points, and failing to launch spirited emotional appeals in defense of progressive issues and hammering down those issues from the "bully pulpit."
Wojtek