The survey finds Clinton topping Trump 47% to 42% among likely voters with Libertarian nominee Gary Johnson at 7% and Green Party nominee Jill Stein at 2%.
Clinton's boost in the race stems largely from gains on Trump among men (from a 22-point deficit with that group in early September to just a 5-point one now) and sharply increased support from independents, who broke heavily in Trump's favor in the early September poll but now tilt Clinton, 44% to 37%.
Clinton has even gained somewhat among whites without college degrees, who have been among Trump's most ardent supporters. She trails Trump by 21 points among that group now, down from a 44-point chasm in early September.
Although most interviews in the survey were completed before Saturday night's revelation that Trump may have avoided income taxes for nearly two decades, the results were clear that about three-quarters of voters think Trump should release his tax returns for public review (73% say so, including about half of Trump's own supporters, 47%).
More respondents also see Trump's refusal to release this taxes as a sign that he's hiding something than that he's under audit from the IRS (57% say he's hiding something, 33% that he's holding back due to an audit).
Voters are in near-universal agreement, though, that paying taxes is every American's civic duty. Nearly 9-in-10 feel that way while just 12% say they see taxes as an unnecessary burden to be avoided. Even among Trump backers, 79% see them as a civic duty.
The poll, conducted entirely after last Monday's presidential debate, finds Clinton's supporters increasingly enthusiastic about voting for president this year (50% are extremely or very enthusiastic now, up from 46% earlier in the month), while Trump backers' enthusiasm has ticked downward, from 58% to 56%.
Some of Clinton's edge in this poll can be attributed to the effects of that enthusiasm shift on the makeup of the likely electorate.
In the early-September poll, Clinton's backers were less likely than Trump supporters to be classified as likely voters because of the responses they gave to questions about their interest in the contest, intention to vote, and past vote history. That resulted in a sharp shift to Trump when assessing preferences among likely voters rather than registered voters.
This time around, her voters are no less likely than Trump voters to qualify as likely voters.
Voters are about evenly split between issues and personal qualities when asked which will be more important in their choice for president, according to the poll, and Clinton gained ground on both sides of that question post-debate.
Clinton has narrowed Trump's edge on handling the marquee issues of the economy and terrorism while increasing her edge on foreign policy, immigration and improving life for racial and ethnic minorities.
Trump tops Clinton by four points as better able to handle trade with other countries, a topic that was one of few high points for Trump in the debate, while Clinton has the upper hand, narrowly, on several other issues raised in Monday's debate, including taxes (48% Clinton to 46% Trump), the criminal justice system (48% Clinton to 45% Trump), ISIS (48% Clinton to 44% Trump).
The debate appears to have worsened voters impressions of Trump personally, 59% of likely voters now see him unfavorably, up from 54% in early September, while Clinton's favorability rating has held fairly steady, standing at 43% favorable to 54% unfavorable.
Trump has lost ground against Clinton when registered voters are asked which candidate is the stronger leader, 45% say Clinton is, 43% Trump. Trump held an 8-point edge on that question in early September.
Clinton has widened her edge as the one with the right temperament for the job, topping Trump by 27 points on that score now, up from a 20 point lead in early September. She also holds wide leads as better prepared (+22), more in touch with middle class problems (+17), having a clear vision for the country's future (+7) and being better able to handle the responsibilities of commander in chief (+6). Clinton has also narrowed the gap on honesty, and now stands 7 points behind Trump on that, though a sizable 15% say neither is more honest and trustworthy.
A stunning 29% of registered voters say neither Trump nor Clinton is a person they admire, about on par with the 30% who see Trump as the more admirable of the pair, behind the 40% who name Clinton as more admired. Among younger voters, a traditionally Democratic group Clinton has struggled to win over, a full 42% say neither candidate is a person they admire, more than name Clinton (37%) or Trump (21%).
Confirming the results of the CNN/ORC poll of debate watchers released shortly after the debate ended, the new survey finds about 6-in-10 voters say Clinton did the better job Monday night, just 24% thought Trump did. Among those who said they watched, 63% said Clinton was the victor, about the same as in Monday night's survey.
The CNN/ORC Poll was conducted by telephone September 28 through October 2 among a random national sample of 1,501 adults. Results among the 1,213 likely voters have a margin of sampling error of plus or minus 3 percentage points. It is 2.5 percentage points among the 1,335 registered voters interviewed.