Jeb Bush probably tanked his presidential hopes by copying Donald Trump's use of the term "anchor baby" to describe a child born to immigrants in the US. Trump went on to describe how he would kick all immigrants out of the country. All. Right away.
"What about the children? Do you think families should be separated?"
"Well, no, " Trump replied. "But they all have to leave."
Donald Trump raises cognitive dissonance to a higher level. That's where you say one thing while you believe the opposite to be true. Trump changes what he says depending on the mood he's in. Maybe this should be called "emotional dissonance".
Trump doesn't have any chance to become President, despite those polls, because his unfavorable ratings--these are people who just plain don't like him--are over 50%. You have to win at least 51% of the vote, generally speaking, if you want to win the election.
But Jeb! has been considered the establishment choice for several months now, despite low poll numbers--$100 million in attack ads should take care of that. One reason the Republican party likes him so much is because he appeals to Latinos. His wife is a Latino. That's why his use of offensive racial slurs is so surprising, and also so harmful to his candidacy. The Republican establishment likes him because they think he can win the key swing state of Florida, but if he keeps on offending Latinos, they could go looking for someone who doesn't.