Here's some poll data that I don't believe has received much attention.
"If [see below] wins the Democratic/Republican nomination for president would you definitely vote for him/her in the general election for president in 2008, would you consider voting for him/her or would you definitely not vote for him/her?"
PERCENT SAYING "DEFINITELY WOULD NOT"
Obama -- 39%
Clinton -- 41%
Edwards -- 43%
Giuliani -- 44%
McCain -- 45%
Thompson -- 54%
Romney -- 57%
What's does that mean?
1. Sen. Hillary Clinton is no more polarizing than other Dems, and less polarizing than every leading Republican.
2. Further, every Dem is less polarizing than every Republican, even the sainted John McCain and Rudy Giuliani. Yet there has been no punditocracy discussion of whether McCain, Giuliani, Thompson "can win" either nationally or in certain areas of the country.
3. Pundits do sometimes discuss Romney's electability, but that's only because there has been discussion of whether a Mormon can win the presidency. (And the particularly high negative for Romney indicates that anti-Mormon bigotry is something he still needs to address head on.)
4. Having said all that, the whole question of polarization when gauging presidential candidates is obsolete. In today's political and media landscape, any candidate will be (and is) rejected by 40% of the country on Day 1.