Ohio Sen. Rob Portman was a distant second, with New Jersey Gov. Chris Christie and Wisconsin Rep. Paul Ryan tying for third.
The survey was sent to the state's 54 directly elected GOP delegates and its 54 alternates, as well as the 12 delegates and 12 alternates elected at the state party's convention in June.
Of the responses, 42.9 percent preferred Rubio. Another 12.2 percent selected Portman. Christie and Ryan received 10 percent of votes, respectively. Former Secretary of State Condoleezza Rice was fifth, with 8.2 percent of votes.
