Back when Tiger Woods was far and away the best golfer on the planet, one of the things that people used to say about him was that he was the most “mentally tough” athlete on the planet. However, as his career went on, people started to notice something about Tiger – although he was great on Sunday when he entered the day with a lead, he was summarily incapable of coming from behind and snatching a final day win, at least in a major. Tiger, it turned out, was a great front runner, but not great at coming from behind, at least when the spotlight glared brightest.

Enter Jeb Bush, who was supposed to have carried the mantle of frontrunner to the nomination, if he was to get the nomination at all. Jeb’s candidacy never excited anyone in particular on the merits, and his basic appeal boiled down to being able to raise a ton of money and swamp the other candidates in the primaries, and his alleged ability to perform well in the general.

This kind of resume essentially depends for its success – especially in a field this crowded with quality candidates – upon the aura of inevitability. For a fairly lengthy amount of time, Jeb carried that mantle well, holding a slim lead over the field and staying in the 15-20% range.

However, Jeb Bush has now failed to crack double digits in two of the last three polls, and he has now fallen behind Ben Carson in the RCP average. After struggling to come to terms with the candidacy of Donald Trump, he of late has changed tack and taken on Trump directly. The early returns have indicated that he is losing that confrontation decisively. Jeb’s team remains publicly confident that they are running a tortoise v. hare race, but the problem is that the rest of the field isn’t sleeping, and Jeb’s basic appeal can’t really afford falling back into the pack of also-rans. His aura of inevitability is basically all he has.

Jeb’s supporters and campaign operatives are pointing to the Romney 2012 campaign as a blueprint for their success. They reason that, at various points, Romney fell behind Rick Perry, Newt Gingrich, Rick Santorum, and Herman Cain, and ultimately prevailed. However, a closer examination of the 2012 race shows that Jeb’s plight is not really similar to Romney’s at all. Here are the RCP averages for the entire 2012 campaign:

If you’ll notice, Romney never really fell below the 18% mark, and never fell below second place. From his nadir in September 2011, when Rick Perry mounted the main true threat to his nomination, Romney actually began consolidating support, even as various challengers (in order, Cain, Gingrich, and Santorum) took brief turns in the lead. While other candidates experienced brief flashes in the pan, Romney continued to slowly and steadily climb upwards, gradually peeling off support from some portion of the candidates who slowly dropped out of the race or flamed out under the public spotlight.

This reflected Romney’s consistent strength as a second-or-third choice option among Republican primary voters, that remained consistent throughout the race. Jeb also once was the clear leader in “second choice” votes early in this campaign, but in recent polling has fallen behind Trump, Rubio, and Carson as the “second choice” candidate as well – indicating that Jeb does not have a readily available pile of votes to draw from if some other candidate (especially Trump) faces a scandal or some other event that precipitates a drop in the polls.

Other candidates in the race began the campaign as underdogs and it seems reasonable to assume that they stand a chance of riding an unexpected wave to the top of the pile before this especially chaotic primary season unfolds. But that’s simply not how the Jeb campaign was build and sold and it’s hard to imagine Jeb getting off the mat to win this race when it’s all said and done.