After Donald Trump suggested that all Mexican immigrants are rapists and criminals, he went on to insist that he "will win the Latino vote."

Well, Gallup's survey results for the past month and a half are in, and Hispanic Americans have responded with a very clear "nope."

This is a disaster for Trump. The billionaire's disapproval is so enormous that Gallup had to more than double the width of its graph just to fit it all in. Meanwhile, Jeb Bush — widely considered the Republican establishment's frontrunner — is coasting with a net approval rating of 11 percent. (Still, besides Trump and Bush, the candidates aren't well-known yet, so their approval ratings could change a lot as they gain more name recognition.)

Hispanic voters are an increasingly important demographic for both political parties, since they're expected to make up more and more of the electorate in the next few decades and are already a prominent force in several battleground states. Political opinion research group Latino Decisions has estimated, for instance, that a Republican presidential candidate will need more than 40 percent of the Hispanic vote to win the election. That's one reason the GOP vowed to reach out to Hispanic voters after its loss in 2012. So it's a huge concern for the party that Hispanic voters really don't like Trump.

It's especially concerning for Republicans because Hispanic voters seem to really, really like Hillary Clinton. Gallup found that the Democratic frontrunner has a very strong 40 percent approval rating among Hispanic Americans.

This is a very good showing for Democrats — Clinton is essentially the polar opposite of Trump, with very strong support among Hispanic Americans. But it's also a bit of a bummer for the lesser-known Democratic challengers — especially former Maryland Gov. Martin O'Malley, who has been trying really hard to win Hispanic voters, and has some solid street cred on immigration issues (although Clinton surprised immigration activists with her very aggressive stance on immigration reform). Still, Clinton is the only well-known candidate among the Democratic campaigns, so the other candidates' ratings could fluctuate a lot as the campaign develops.

All of this goes to show that the conventional wisdom on Trump seems to be right: He may lead the polls for the Republican nomination for the time being, but if he were to go to the general election, he would face very tough odds against a Democrat who has much more favorability among a very important demographic.