A new Quinnipiac University poll shows Clinton up five points overall -- a number that is close to her average lead in the Real Clear Politics average and is four points bigger than her one-point lead in a Quinnipiac poll conducted just before the debate.
The big reason she's extended her lead: Independent voters. In the Q poll conducted Sept. 22-25, Trump led them by 7 points, 42-35, and in a poll two weeks prior, he led them by 5.
But in the new poll, conducted Monday through Wednesday of this week, Clinton has asserted a 14-point lead among this previously Trump-friendly group, 46-32.
And if you exclude third-party candidates, Clinton has turned a four-point deficit before the debate into a 20-point lead, 57-37 -- a net shift of 24 points.
Those numbers echo what we saw from CNN/Opinion Research polling earlier this week. After showing Trump leading independents by 20 points in early September, Clinton took a 7-point lead, 44-37, in a poll conducted late last week and through the weekend.
And again, the shift is bigger if you exclude third-party candidates, from a 21-point Trump lead (55-34) to a 9-point Clinton lead (50-41). That's a net shift of 30 points.
It's worth noting here that crosstabs like this -- and especially those measuring independents -- have a way of bouncing around a lot in polls of the presidential race. These are the two high-quality polls we have right now that offer direct comparisons to before the debate, and they both show similarly big shifts. But we'll have to away more data to see if it holds. (Update: Polling done by the Public Religion Research Institute and The Atlantic shows Trump still leads Clinton by 8 points among independents. He led by 9 points before the debate. This poll includes smaller samples, though, including among independents.)
At the same time, the idea that Trump would lose ground with independents is precisely what Republicans are worried about at this point, after a week in which the Clinton campaign has successfully baited him into making a series of ill-advised comments about former Miss Universe Alicia Machado. Trump also speculated about the Clintons' marriage and was otherwise just plain erratic.
And as the New York Times's Jonathan Martin and Alexander Burns wrote earlier this week, internal polling was already showing independents heading for the hills:
But private polling by both parties shows an even more precipitous drop, especially among independent voters, moderate Republicans and women, according to a dozen strategists from both parties who spoke on the condition of anonymity because the data was confidential.
Liesl Hickey, a Republican strategist involved in several House races in swing states, said she was dismayed by a sudden exodus of independent voters in more diverse parts of the country.
“They are really starting to pull away from Trump,” said Ms. Hickey, describing his soaring unpopularity with independents as entering “uncharted territory.”
The apparent shift toward Clinton among independent voters just isn't something Trump can sustain. Given there are more registered Democrats than Republican in American elections, Republicans generally must win independent voters in order to even have a chance. Back in 2012, for instance, Mitt Romney won independents by 5 points even as he lost the race overall by 4.
In other words, if the independent numbers in these two polls hold up, it's going to be very, very difficult for Trump to win.