A political party (and any organisation that seeks to field candidates for office is a political party, whether it claims otherwise or not) needs two things:
The founder of AE, Peter Ackerman, seems to have an ample supply of the former - he made over $300 million as a director at the junk bond trading firm Drexel Burnham Lambert, before the company filed for bankruptcy in the wake of a securities fraud investigation, and his disputes with the IRS over $150 million in allegedly unpaid taxes suggest that he's at least as wealthy in recent times as he was at the collapse of Drexel.
It's in the second category, footsoldiers, that AE seems to have been lacking. The AE website is, at this point, little more than a holding page, but at the time of AE's withdrawal from the 2012 presidential race, its effort to find a presidential candidate with widespread support had been singularly unsuccessful:
source: Daily Kos
This is not, to be honest, surprising. People who decide to invest their time and energy in causes do so because they are passionate about them, and AE's founding principle - that politics in the US is too partisan and polarized - may not be particularly inspiring to such people; few are passionate about being somewhere in the middle.
AE did, however find one candidate to support for election: Angus King, who was subsequently elected as Senator for Maine. A complaint about alleged irregularities in AE's support for King was filed with the FEC by the Republican Party of Maine as a result of this support.