Winner: Donald Trump Primary date: May 10, 2016
Poll source Date 1st 2nd 3rd Other Primary results [ 1] [ self-published source ] May 10, 2016 Donald Trump 77.01% Ted Cruz 8.98% John Kasich 6.74% Ben Carson 2.17%, Marco Rubio 1.43%, Jeb Bush 1.14%, Rand Paul 0.89%, Mike Huckabee 0.87%, Chris Christie 0.36%, Carly Fiorina 0.33% R.L. Repass & Partners/MetroNews [ 2] Margin of error: ± 4% Sample size: 228
April 22– May 2, 2016 Donald Trump 57% Ted Cruz 25% John Kasich 14% Undecided 4% Public Policy Polling [ 3] Margin of error: ± 4.2% Sample size: 549
April 29– May 1, 2016 Donald Trump 61% Ted Cruz 22% John Kasich 14% Undecided 3% Metro News [ 4] Margin of error: ± ?% Sample size: 159
February 11–16, 2016 Donald Trump 40% Ted Cruz 20% Marco Rubio 15% Ben Carson 10%, John Kasich 6%, Jeb Bush 4%, Carly Fiorina <1%, Chris Christie <1%, Not Sure 4% Orion Strategies [ 5] Margin of error: ± 4.9% Sample size: 406
August 25, 2015 Donald Trump 29% Marco Rubio 8% Ben Carson 7% Jeb Bush 7%, Mike Huckabee 7%, Ted Cruz 5%, Scott Walker 2%, Carly Fiorina 2%, John Kasich 1%, Rand Paul 1%, Undecided 32% Harper Polling [ 6] Margin of error: ± 6.3% Sample size: 242
April 9–11, 2015 Jeb Bush 23% Mike Huckabee 20% Scott Walker 13% Ben Carson 8%, Ted Cruz 8%, Rand Paul 7%, Chris Christie 5%, Marco Rubio 4%, Rick Santorum 1%, Undecided 11%