Poll: Ben Carson Tied For Lead With Donald Trump in Iowa

Neurosurgeon Ben Carson has surged into the spotlight.

A new poll released Monday shows Ben Carson tied with Donald Trump for the lead in Iowa with 23 percent support, marking the first time since mid-July that an Iowa poll has shown Trump not alone in the lead.

The Monmouth University poll shows the surgeon's support has unexpectedly increased by 15 points since the organization's previous poll in mid-July. Meanwhile, former Iowa frontrunner Scott Walker has dropped 15 points to fifth place now.

Businesswoman Carly Fiorina holds third place in the new poll with 10 percent support, although criteria for the debate on CNN among the top 10 candidates threatens her ability to grab a podium.

The three candidates in the Republican field who have never held elected office now fill the top three spots in Iowa, so it's no surprised that two-thirds of GOP voters say they want an outsider who can bring a new approach to Washington over someone with government experience who knows how to get things done.

Carson's favorability rating is the strongest in the field: eight in 10 Republican voters see him favorably; only 6 percent don't. But his spike in the polls comes despite campaigning in Iowa only four days since the first Republican debate on Aug. 6, one of which was his Iowa State Fair appearance.

Ted Cruz is in fourth place in the poll with 9 percent support, while Jeb Bush has sunk to 6th place with 5 percent of the vote. Bush is the only GOP candidate to garner a majority unfavorable rating in Iowa, up nine points to 51 percent since mid-July.

ABC's Katherine Faulders contributed to this report.