As of Monday, Roy said, American Future Fund had spent $460,000 on that ad alone in Illinois—which votes March 15, along with Florida and Ohio—and would be buying another $550,000 worth of the hits this week. He indicated that the group’s internal numbers showed Trump is vulnerable in Illinois, in addition to Florida, where Rubio has shown some upward momentum as of late.

Exactly which GOP candidate can defeat Trump with the help of these ads is of little consequence to American Future Fund in the immediate future, however.

“If we can defeat him in any particular state, let the chips fall where they may,” Roy said.

That also seems to be the motto of Club for Growth Action, which has spent some $2 million in Illinois and an additional $1 million in Florida to derail the frontrunner.

“What our experience has shown is when voters get the information—so, when they see the ads that we’re doing and that some of the other groups are doing—Trump’s support has a floor in the high 20s, low 30s, but it falls off,” David McIntosh, the president of Club for Growth, told The Daily Beast. “And then the voters now are looking around to say, ‘Who’s the most viable alternative?’ You’re creating almost an anti-Trump vote. They’re looking to see where to place it where it will have the biggest effect. Right now Cruz is benefiting from that. In Florida, I think it’ll help Rubio.”