IMHO, this theory is way down the list and likely immaterial.
The overwhelming reason the Republicans lost is that they defeated themselves:
1) Scandals - Foley, Ney, Taft, DeLay (BS charges but he should have known better), Allen, Cunningham, Abramoff, Haggard, et al. Never mind the media's role and never mind that the Dem's were chest deep in it too - we are to blame because we didn't police ourselves. If we do, then the media has no credible fodder. This time they had plenty and were able to make the most of it.
2) They didn't walk the walk on conservative issues - smaller government, immigration control, fiscal restraint.
However, this is cause for optimism - we control our own destiny. All we have to do is stay clean enough and govern like Conservatives should. We then cream the libs in the battle of ideas, and they have no ammunition for counter-attack.
The scandals on the right are fully met by scandals on the left. But nobody in the press is suggesting that John Edwards scandals tar the entire Democratic party, the way that Foley et. al. was used to tar the Republicans. That difference is the result of a full court press of electioneering.
It's an Alinsky technique to hold the other guy to impossible standards. Your 'police ourselves' approach could never have done enough to please they left. They would have found fault even if we ran Mother Teresa as a candidate.
Sen. Stevens of Alaska was one of the scandal victims, until after he'd lost and we found out that the prosecutors held back evidence showing he was innocent. So staying clean isn't sufficient.
Yes, they didn't always walk conservative. But a steady drumbeat of propaganda doesn't help keep the conservative on the straight and narrow.
The battle of ideas is not just an every-4-years election campaign. It's an on-going thing, and we aren't in it. George Bush I and II both totally ignored it. And that's the thesis here. There's a continued battle of ideas, and the Soros crowd are in it constantly and at high volume and intend to win. We are getting shouted down. You can't win in the battle of ideas if you aren't heard.