A super-PAC working on Bush’s behalf has also failed to convince would-be endorsers through its massive advertising efforts. Since Sept. 1, Right to Rise has purchased 3,749 TV spots in Iowa TV markets at an estimated cost of more than $3 million, according to data compiled by the ad tracking firm Kantar/CMAG. This makes the super-PAC the largest ad buyer in the state by far. The next closest competitor (the pro-Bobby Jindal group Believe Again) had bought just half as much in Iowa before their candidate dropped out of the race.

Yet even as Right to Rise has poured millions into the race, endorsements for Bush have slowed, with only two national elected officials lending their names to his cause in November. Senator Marco Rubio, whom many election watchers see as Bush’s chief rival for establishment support, racked up nine new endorsers this month, more than doubling his previous slate.

On the debate stage, where a strong performance could lure more high profile endorsements, Bush hasn’t done himself any favors. 

“His performance in the debates is what was weak to say the least, and that made some people think twice,” said Cohen, of James Madison University.