In a head-to-head matchup with Trump, Clinton got the support of 51 percent of likely voters, compared with 41 percent for Trump, according to the Quinnipiac University poll. Once the Libertarian Party's Gary Johnson and Green Party's Jill Stein are included, Clinton's lead drops to seven points.
The university conducted the poll from Aug. 18-24, after the Trump campaign's latest leadership change was announced on Aug. 17. The Republican nominee's campaign appointed Breitbart News' Steven Bannon its CEO and named Kellyanne Conway its campaign manager in an effort to focus its message.
Other recent polls showed a narrower lead for Clinton. A Reuters/Ipsos poll taken from Aug. 20-24 showed Clinton with a 7-point lead in a head-to-head matchup. An Economist/YouGov poll taken Aug. 19-24 suggested only a 3-point lead for Clinton.
Both candidates still struggle with getting voters to like them, the Quinnipiac poll suggests. Only 44 percent of likely voters said they liked Clinton "a lot" or "a little," while 47 percent said they disliked her "a lot" or "a little."
Trump fared even worse, with only 35 percent of likely voters saying they liked him while 53 percent said they disliked him.
The poll shows Clinton with a 60 percent to 36 percent lead among women, while Trump has a 48 percent to 42 percent lead among men. Trump holds an 11-point advantage among white voters, while Clinton holds a 62-point lead lead among non-white voters, the poll suggests.
Likely voters also found Clinton more qualified for the job than Trump.
Sixty-two percent of respondents said Libertarian nominee Gary Johnson should be included in the presidential debates.
The telephone poll included about 1,500 likely voters and had a margin of error of plus-or-minus 2.5 percent.