Well, he’s not leading in the polls...
Funny thing about polls... It identifies the targets for the candidates with money.
If you recall the 2012 primary, early polls kept shifting. Gingrich shot up because of his debate performance, but he didn't have the campaign warchest of Mitt Romney. Romney rode out the low polls until "super Tuesday," when he carpet bombed Gingrich with negative ads.
Gingrich dropped out the following week. He didn't have the funds to continue, despite his polling.
I have a feeling that Jeb Bush is similarly positioning himself. He'd like to be higher in the polls, but he has the funds to clear the field and be the choice by process of elimination, if not popularity.
The problem is Trump, who is popular and also has the funds to ride it out, regardless of polls. And if it comes down to two left standing, Bush and Trump...?
-PJ