Sixty percent said if no candidate has won a majority after the first round of voting at the convention, the delegates should vote for the candidate with the most support in the primaries and caucuses, while 38 percent said the delegates should vote for the person they feel would be the best candidate, according to a CNN/ORC poll released this week.

Mr. Trump has warned against denying him the GOP presidential nomination if he heads into the convention with the most delegates. The latest tally, according to The Associated Press, has Mr. Trump with 680, Sen. Ted Cruz with 424 and Ohio Gov. John Kasich with 143.

Overall, Mr. Trump led the field with 47 percent support, with Mr. Cruz at 31 percent and Mr. Kasich at 17 percent.