Hillary Clinton won our closely-divided straw poll, with 52.2% saying she won the debate vs. 47.8% for Donald Trump. 9,201 votes were cast (after duplicate submissons were removed) in this non-scientific survey.
When we reported preliminary results Tuesday morning, Trump was leading 50.8% to 49.2%. As we dug into the numbers, we found Trump did much better among those that voted just after the debate, while Clinton got stronger as the hours went along. About 50% of votes were cast between the debate's end and 1AM ET, with Trump winning by about 52-48%. Thereafter, Clinton won by 56-44%. That 8 point swing gave Clinton the four point overall margin.
Since we didn't ask other questions, it is hard to know the reason for this shift. However, we don't recall ever seeing anything close to this kind of a time-based change of opinion in our prior straw polls. For whatever reason, first impressions did not last after Monday's debate.