Trump earned 24 percent compared to 17 percent for Ben Carson. In third place is former Florida Gov. Jeb Bush with 10 percent, followed by Florida Sen. Marco Rubio at 8 percent, Carly Fiorina and Ohio Gov. John Kasich at 7 percent each, New Jersey Gov. Chris Christie at 5 percent and Texas Sen. Ted Cruz and Kentucky Sen. Rand Paul at 4 percent. Other candidates drew no more than 1 percent support, with 9 percent undecided.

The poll represents a blow to Bush, whose favorability rating in the state dropped to its lowest level in almost a year of polling despite a big ad buy from the Right to Rise super PAC supporting him. About 57 percent said they had a favorable view of the former governor, down from 59 percent in May and 61 percent last November.

Still, a plurality of 22 percent of voters said Bush is prepared to be president, tied with Trump. But the Manhattan real estate mogul is seen as the best candidate to deal with Russian President Vladimir Putin, earning 31 percent with that question, followed far behind by Bush at 13 percent.