Donald Trump is still the Republican frontrunner for the presidential nomination - and GOP leaders are concerned with the businessman's controversial comments.

With Trump having an unfavorable rating of 74 percent with minority voters, according to ABC News, he could hurt the Republican party's chances to broaden its voter base. His comments about Mexican immigrants have further hurt the GOP's attempts to get more Latino voters.

"If he carries this message into the general election in Ohio, we'll hand this election to Hillary Clinton - and then try to salvage the rest of the ticket," said Matt Borges, chairman of the Ohio Republican Party, according to the New York Times.

Fellow Republican presidential candidates also think Trump would be a poor choice for a nominee.

"It would be an utter, complete and total disaster," said South Carolina Senator Lindsey Graham, according to the New York Times. "If you're a xenophobic, race-baiting, religious bigot, you're going to have a hard time being president of the United States, and you're going to do irreparable damage to the party."

Political scientists note that Trump is resonating with voters  but are unsure if they will vote for him in the primaries.

Trump and [fellow Republican candidate] Ben Carson are banking on the fact that people who are turned off by politics are going to rally and get behind them. But political scientists have long known that people who are turned off by politics don't engage (in) the system," said American University political scientist Jennifer Lawless, according to CNN.

On the other hand, some Republicans think Trump could be a viable candidate who can succeed in getting the Republican nomination. "I think he is going to continue to surprise people," said Bill Miller, a veteran Republican political consultant from Texas, according to CNN. "The question about Trump is: Can he go the distance? We will see. But I would not sell him short."