Poll: Ben Carson leads Donald Trump by double digits in Iowa
Washington (CNN)A new poll out Monday confirms that Ben Carson is topping Donald Trump in Iowa's Republican caucuses -- this time by 14 points.
According to the Monmouth University poll released Monday, Carson is leading Trump 32% to 18% among likely Republican Iowa voters. In a Monmouth poll conducted in August, the two had been tied at 23%.
The poll confirms a shift in the state identified by two other polls in the past week. In the Des Moines Register/Bloomberg poll, Trump was up 9 points, and Quinnipiac University showed him up 8 percentage points.
RELATED: Two polls show Carson on top in Iowa
Trump has begun to attack Carson on the trail as the retired neurosurgeon rises in the polls and challenges Trump's front-runner status, though the mogul continues to lead nationally. Trump maintains that he only "counterpunches," but Carson has not been making Trump a focal point of his campaigning in recent weeks.
The poll had good news for other GOP candidates, as well. Florida Sen. Marco Rubio has picked up 6 percentage points since August, to 10%. That's good enough to tie for third place with Texas Sen. Ted Cruz. Jeb Bush has picked up three points to be in fifth place, at 8%. His favorability rates have also improved 8 points since August.
On the other hand, Carly Fiorina's post-debate bounce has seemingly ebbed, as she dropped from 10% in August to 5% in Monday's poll.
Monmouth surveyed 400 likely Republican Iowa caucus-goers from October 22-25 for the poll. which has a margin of error of plus or minus 4.9 percentage points.