The poll is the first in Iowa this month to not show Trump in the lead all alone and provides further evidence of Carson’s growing support.
Carson has the best favorability rating in the field with 81 percent saying they have a positive view of him and only 6 percent who saying they view him unfavorably.
Trump leads among Tea Party conservatives and men, but Carson leads among women and Evangelicals.
“After more than a month of Trump winning virtually every Republican demographic group, we’ve finally got a little variation in voting blocs to talk about,” said Monmouth University pollster Patrick Murray.
The recent survey is also the third consecutive poll of Iowa to find Trump and Carson at the top of the field. They are also in the first and second place nationally according to the RealClearPolitics average of polls.
This poll, along with others, shows the degree to which political outsiders are dominating in the early stages of the race for the Republican presidential nomination.
Businesswoman Carly Fiorina is in third place with 10 percent followed by Sen. Ted Cruz at 9 percent. Wisconsin Gov. Scott Walker’s slide in the polls continued as he fell to fifth place.
Former Florida Gov. Jeb Bush has 5 percent support and the worst favorability ratings in Iowa. Ohio Gov. John Kasich and Florida Sen. Marco Rubio tie each other at 4 percent. Kentucky Sen. Rand Paul received 3 percent. Former Arkansas Gov. Mike Huckabee and former Pennsylvania Sen. Rick Santorum both took 2 percent support.