As usual, if not-a-candidate Biden decides once and for all not to be a candidate, it's Clinton who sees more benefit. Without Biden, she jumps up to 54 percent in the Fox polls, while Sanders only goes to 28.
That said, this is a good poll for Clinton. Like an emergency room doctor, she will be happy to have stopped the bleeding. But it also offers other reasons that her campaign might feel better about its long-term prognosis.
If you compare Fox's late-September poll to this one, Clinton saw some slight gains with certain demographics -- and Sanders saw some big drops. Bearing in mind the larger margins of error here, here's the change by demographic group since September.
Sanders is down five points overall. He's down 12 points with people under the age of 45 and down nine points with men. He's down 13 points with people who make more than $50,000 in income -- while Clinton gained 13 points with those who have a college degree.
Part of the overall change, incidentally, was an increase in people who say that they don't know who they'll support -- a reminder that Tuesday's debate could shuffle the stage pretty significantly. (Martin O'Malley is at one percent here; odds are good that will increase.)
But, again: For October 2015 Hillary Clinton, successfully applying the brakes to the car skidding down the hill is a pretty decent position. And for October 2015, big drops with the college-educated and wealthy are the sort of storm clouds Sanders was hoping wouldn't appear.
I have a lot more metaphors, by the way, but I need to save some for the debate.