Retired neurosurgeon Ben Carson has forged ahead of businessman Donald Trump as the front-runner in the race for the Republican Party's 2016 presidential nomination, a Wall Street Journal-NBC News poll said Monday. This is the first time since June the poll showed anyone besides Trump to be the top choice of GOP voters.

The new poll showed that 29 percent of Republican primary voters support Carson, the highest percentage held by any candidate so far in the survey. Trump was second with 23 percent. Other polls have seen Trump's support drop, but the Wall Street Journal-NBC News poll was the first national poll to show Trump in second place.

Carson has already shown the potential to beat Trump in an important early voting state. A Monmouth University poll released last week surveyed Iowa Republican caucusgoers, and found that Carson boasted a double-digit lead over Trump. The former neurosurgeon earned 32 percent of the vote, while Trump held second place with 18 percent.

But an Associated Press-GfK poll published last Monday found that Trump was viewed as the most electable candidate, with 7 in 10 Republican registered voters saying he could win the office if he gains the party's nomination.

In the new Wall Street Journal-NBC News poll, Florida Sen. Marco Rubio followed in third with 11 percent of the vote, and Texas Sen. Ted Cruz was fourth with 10 percent. Former Florida Gov. Jeb Bush received 8 percent of the vote.

Full results of the survey will be published at midnight Monday. 

The poll was conducted Oct. 25-28, overlapping with the Oct. 28 Republican presidential debate hosted by CNBC. It has a margin of error of plus or minus 4.9 percentage points among the 400 Republican primary voters polled.