Republican front-runner Donald Trump is widely unpopular among the nation’s Hispanics, a new AP-GfK poll finds, challenging the billionaire’s oft-repeated assertion that he will win the Hispanic vote if he becomes his party’s nominee.

The survey finds many of the Republican candidates running for president would probably struggle to win significant support among Hispanics in a general election. Jeb Bush and Marco Rubio are their favorites, but even they are a hard sell, the poll suggests.

Even so, most in the field are unknown to enough Hispanics that they might have a shot at proving themselves.

That’s a particular struggle for Trump, who began his campaign for president by calling some immigrants from Mexico rapists and has vowed to deport all of the estimated 11 million people living in the country illegally if he is elected president. Trump is viewed unfavorably by 72 percent of Hispanics, with 6 in 10 having a very unfavorable opinion of him, the AP-GfK poll finds. Only 11 percent view him favorably.