Fox News' first post-debate poll shows businessman Donald Trump holding his position atop the GOP presidential field, while a trio of establishment favorites - Jeb Bush, Scott Walker and Marco Rubio - continue to lose ground.

Trump earned 25 percent support among GOP primary voters, down one point since before the first Republican debate on Aug. 6. Trump's support among women fell from 24 percent to 21 percent in two weeks, likely in part due to a very public and some say misogynistic spat with Fox News host and debate moderator Megyn Kelly. Trump was once again rated as the least likeable Republican candidate.

Another political newcomer, retired neurosurgeon Ben Carson, took second place in the poll with 12 percent. Carson saw a five-point jump in the polls compared to a Fox poll released immediately before the debate, or a 71 percent increase over where he stood just two weeks ago, notes The Washington Post. One of the GOP's most anti-establishment senators, Ted Cruz of Texas, also ticked up in the poll after the debate, coming in third with 10 percent compared to his previous 6 percent.

Bush, a former Florida governor, saw the biggest drop of any candidate following the debate, down from 15 percent in the Fox poll conducted before the debate to 9 percent now, in single digits for the first time since April. Walker, the Wisconsin governor, tied for fifth place with former Arkansas Gov. Mike Huckabee, both receiving 6 percent. That's the lowest support Walker has seen in more than a year, down nine points from earlier this month, according to Fox.

Former Hewlett-Packard CEO Carly Fiorina, who was viewed as the winner of the undercard debate, jumped from 2 percent to 5 percent. Ohio Gov. John Kasich and Rubio, a Florida senator, tied with 4 percent. New Jersey Gov. Chris Christie and Sen. Rand Paul of Kentucky both received 3 percent.

Respondents rated Fiorina as the winner of both debates, followed by Carson, Kasich and Rubio. Trump was rated as having the worst debate performance, followed by Paul and Christie.

On the Democratic side, front-runner Hillary Clinton dropped below 50 percent for the first time to 49 percent, while Vermont Sen. Bernie Sanders continued to climb, from 22 percent to 30 percent.