There still exists in some parts of the Republican party an idea that Jeb Bush will, ultimately, reemerge as a serious candidate in the 2016 Republican race. That, after all of the Trumping is over, the former Florida governor's slow-and-steady approach will somehow be validated and he will wind up as the party's standard-bearer.

This chart -- built off of new numbers from Gallup polling -- should pour a swimming pool's worth of cold water on that notion.

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Jeb(!) is now regarded more negatively than positively by Republicans and Republican-leaning voters.  That would be bad enough given that it's those voters that Bush needs to woo if he hopes to win the GOP nod. But, it gets worse. Look at the trend line in that chart. In July, 54 percent of GOP voters had a favorable opinion of Bush compared to just 27 percent who saw him in an unfavorable light.

In the intervening six months, Bush's numbers have totally collapsed -- even amid an onslaught of more than $50 million in ads from Right to Rise, a super PAC working to elect him, in early voting states. (Worth noting: Gallup's numbers are national; it's possible, therefore, that Bush's favorable numbers are marginally better in Iowa, New Hampshire and South Carolina. But, still.....)

"Bush's image among Republicans has grown steadily more negative with each passing month since July, and he now enters the 2016 election year with the worst image of any of nine major GOP candidates among the party base -- a trend that is presumably the exact opposite of what his campaign would have wanted," writes Gallup head honcho Frank Newport. Even more troubling for Bush's prospects, adds Newport, is that "there have been no highly publicized incidents, scandals or revelations connected with Bush's campaign since July, and thus no single factor can easily be identified as the culprit for his sharply deteriorated image."

So, in short, Jeb's image has badly eroded among base Republicans despite the fact that he's made no obvious or costly errors and even as a group formed to elect him president has been blanketing the airwaves to promote him.

I've written before about Jeb Bush's "dog food" problem, but the Gallup numbers illustrate it more clearly than anything I've seen of late. Republican voters simply don't want what Bush is selling. And the closer it gets to the time to make decisions, the more convinced they are of that fact.

In an election cycle where Donald Trump is the front-runner to be the nominee of a major political party, I hesitate to rule anything out. So, I can't -- and won't -- say that Jeb can't stage some sort of miraculous comeback to emerge as the party's nominee. But, these numbers -- as well as his polling struggles in Iowa and New Hampshire -- suggest that the climb back to credibility is almost impossibly long and high.