Are the presidential polls skewed?

[nomoon]

Has anyone kept up with the allegation that many of the presidential polls are skewed by under sampling Republicans?

Obviously, there is some guess work in predicting the demographic turnout of likely voters, but one can make some reasonable estimates and boundary conditions based on previous elections. This link states that Rasmussen says that the US is made up of 35.4% Republicans, 34.0% Democrats, and 30.5% Independents (I suppose all other parties are counted as Independents). I would have expected Democrats and Republicans to be roughly equal, so this sounds plausible.

I’ve heard allegations that many pollsters are using the assumption that the next election’s turnout will be the same as 2008 turnout, though currently party enthusiasm suggest otherwise, and that basing polling results on this would produce results overly favorable to Obama. Dick Morris is one person who agrees with this analysis. I’ve heard some Democratic pundits defend the polling sampling, but I didn’t’ understand their argument, and I haven’t yet found a online explanation.

What difference does it make?

If we look at a recent (10/13/12) Washington Post poll, where Obama has a 3 point lead over Romney, we see the following weighting (at the bottom of the link):

Democrat: 35%
Republican: 26%
Independent: 33%

This gives the Democrats at +9 point advantage based on turnout. If the "correct" weighting should have be a +1 advantage for Republicans, should the corrected results show a +7 point lead for Romney? Surely, I'm over simplifying something?

I found a website http://www.unskewedpolls.com/ that claims to show unskewed results for various polls and the results are much more favorable for Romney than the published results.

Any thoughts on this subject?