Thomson Reuters
U.S. Republican presidential candidate Donald Trump gestures after arriving for jury duty at Manhattan Supreme Court in New York
Case in point: His abysmal favorability ratings among Hispanic voters.
A Gallup poll released Monday showed that Trump has, by far, the highest net unfavorable rating of any Republican candidate. By a 51-point margin, Hispanic voters view him more unfavorably than favorably.
That's far higher than the net unfavorability of the next-nearest candidate - former Texas Gov. Rick Perry (R), who Gallup reported has a net unfavorability of 7% among Hispanic voters.
Though many initially scoffed at Trump's run, Republicans are well aware that the current front-runner could spell disaster for the party. At the forefront of their concerns have been his controversial comments about immigration, which culminated in the release of his official immigration plan last week.
The GOP itself has admitted that it will struggle to win elections if the party cannot make inroads with Hispanic voters, who are expected to make up 11% of voters in 2016, and will be proportionally higher in swing states like Colorado.
In his announcement speech earlier this year, Trump claimed the Mexican government was sending "rapists" and drug runners across the US border. He subsequently refused to apologize, despite condemnation from Republican allies and business partners severing ties with him.
Earlier this month, he unveiled an ambitious immigration plan that would end birthright citizenship, a constitutional right that allows all people born in the US to be automatically granted US citizenship.
Thomson Reuters
Republican presidential candidate Jeb Bush speaks at a town hall meeting in North Las Vegas, Nevada
Trump has brushed off criticisms of his inflammatory rhetoric, saying repeatedly that he will "win the Latino vote." To back that up, he typically cites vague promises that he would help foster job growth that would benefit Hispanics and Latinos.
But Trump's poor ratings with Hispanic voters also mirror a larger, looming problem with his candidacy: His failure to appeal to voters outside of his base of support. Despite consistently strong support among Republican primary voters, Trump still has a far higher unfavorability rating among American voters generally.
On the other side of the coin in the Gallup poll, former Florida Gov. Jeb Bush (R), presents perhaps the greatest GOP contrast to Trump. By an 11-point margin, Hispanic voters view Bush favorably - the highest score among Republicans.
"Meanwhile, an interesting shift in Hispanics' ratings of Bush has occurred," Gallup wrote. "His net favorable rating among Hispanics jumped from +1 in July (based on 28% viewing him favorably and 27% unfavorably) to +22 in August (41% favorable, 19% unfavorable), a significant change at a time when no other candidate's image has shown much movement."
But no Republican candidate is viewed as favorably as Democratic presidential front-runner Hillary Clinton, who Hispanic voters see in a favorable light by a 40-point margin.