Still, conventional wisdom about the dominance of super-PACs continues to be upended. In September, after many candidates had already spent months courting mega-donors, Rick Perry and Scott Walker dropped out of the race leaving millions of super-PAC dollars unspent and showing that an outside group couldn’t simply step in for a financially troubled campaign. Meanwhile, Right to Rise, a super-PAC supporting Jeb Bush, has already spent about $45 million, only to see Bush’s poll numbers stagnate. That’s made many traditional Republican donors stay on the sidelines, concerned about the impact their money can have in an environment where not even Right to Rise’s $103 million fundraising haul has been enough to lift a more pro-establishment candidate to the top of the pack.

One of the most significant forces, according to Conway, is the “immovable object of the past five-plus months named Donald J. Trump.”

Ahead in most polls since July, Trump has been the most singularly disruptive force in the Republican race. And he’s done it by spending next to nothing. Instead, Trump has dominated the news week after week, getting hours of free time on the airwaves, known as “earned media” in the industry.

“Paid ads can’t overwhelm earned media. It never could,” said one official with a super-PAC backing a Republican presidential candidate who wasn’t authorized to speak on the record. “All of that stuff is a much louder microphone than anything we have, but in a very real sense the campaign is just starting now.”