From NBC's Mark Murray
Here's the reason why Karl Rove and many establishment Republicans did not want Christine O'Donnell to win last week's GOP Senate primary in Delaware.
A new CNN/Time poll finds Chris Coons (D) leading Christine O'Donnell (R) by 16 points among likely voters in Delaware's Senate race, 55%-39%.
But if Mike Castle, beaten by O'Donnell in last week's primary, were the GOP nominee, he would have an 18-point lead over Coons, 55%-37%.
That's a 34-point swing.
So that's the good news for Democrats in the new batch of CNN/Time polls. Here's the bad news: In Colorado's Senate race, Ken Buck (R) is leading Michael Bennet (D) among likelies, 49%-44%; in Pennsylvania's Senate race, Pat Toomey (R) is ahead of Joe Sestak (D) by a similar margin; and in Wisconsin, Ron Johnson (R) leads Russ Feingold (D), 51%-45%.
Yet here is the silver lining for Dems in these contests: Among registered voters, their candidates are either ahead or tied. Which means one thing: the higher the Dem turnout, the better their candidates will do.
The polls were conducted Sept. 17-21, and -- for the likely voters -- they have a margin of error of plus-minus 3.5% in CO, DE, PA, and plus-minus 3.0% in Wisconsin.