Donald Trump remains the leader in the race for the Republican presidential nomination, but his support has fallen by a third over the past week-and-a-half. Carly Fiorina is now near the front of the pack.

The latest Rasmussen Reports national telephone survey finds Trump with 17% support among Likely Republican Primary Voters, down from 26% in late July before the first GOP debate. Senator Marco Rubio and former Florida Governor Jeb Bush are in second place with 10% support each, in a near tie with Fiorina and Wisconsin Governor Scott Walker who both earn nine percent (9%) of the likely primary vote.

Next with eight percent (8%) come retired neurosurgeon Dr. Ben Carson and Senator Ted Cruz at seven percent (7%). (To see survey question wording, click here.)

Sign up: Free daily newsletter Sign up!

Rasmussen Reports Managing Editor Fran Coombs and spokesman Leon Sculti are available for media comment on these poll results. Call 732-776-9777x205 or send an e-mail to leon.sculti@rasmussenreports.com to schedule now.

Fiorina, former CEO of Hewlett-Packard and the candidate generally viewed as the winner of the B-level debate last Thursday evening, has jumped eight points from one percent (1%) support in the previous survey. [Because there are 17 candidates in the Republican contest, Fox News broke them in to two groups: the top 10 pollwise who appeared in a 9 p.m. Eastern debate and the remaining seven who debated earlier that evening.]

Rubio has doubled his level of support from five percent (5%) in late July. Carson has gained slightly. Walker has fallen back five points, while support for Bush and Cruz has held steady.

(Want a free daily e-mail update? If it's in the news, it's in our polls). Rasmussen Reports updates are also available on Twitter or Facebook.

The national telephone survey of 651 Likely Republican Primary Voters was conducted by Rasmussen Reports on August 9-10, 2015. The margin of sampling error for the survey is +/- 4 percentage points with a 95% level of confidence. Fieldwork for all Rasmussen Reports surveys is conducted by Pulse Opinion Research, LLC. See methodology.

Former Arkansas Governor Mike Huckabee, who ran for the GOP nomination unsuccessfully in 2008, also lost ground among likely primary voters, falling from seven percent (7%) support to three percent (3%) now.

Interestingly, slightly more voters are now unsure about their vote. Seven percent (7%) were undecided a week-and-a-half ago. Now after the debates and the resulting news coverage, 11% feel that way.

The latest survey finds the rest of the Republican hopefuls and their level of GOP primary voter support little changed: New Jersey Governor Chris Christie (4%); Ohio Governor John Kasich (4%); Senator Rand Paul (4%), and all with one percent (1%) support each – former Virginia Governor Jim Gilmore, Senator Lindsey Graham, Louisiana Governor Bobby Jindal, former Texas Governor Rick Perry and former Pennsylvania Senator Rick Santorum. Former New York Governor George Pataki earned 0% support statistically in this survey.

In late July, Trump earned 30% of the male vote and had 22% support among women. He now earns 19% and 14% support from these two groups.

Age-wise, the billionaire developer’s support is strongest among middle-aged voters.

Trump continues to say he may run as a third-party presidential candidate if he does not win the GOP nomination, and at least prior to the debate last week, he had sizable support for a third-party run among likely GOP voters.

Additional information from this survey and a full demographic breakdown are available to Platinum Members only.

Please sign up for the Rasmussen Reports daily e-mail update (it’s free) or follow us on Twitter or Facebook. Let us keep you up to date with the latest public opinion news.