Conservative PACs spent about $1.3 million attacking Donald Trump in the fall—a pittance compared with the tens of millions they spent fruitlessly trying to keep Jeb Bush’s doomed presidential bid buoyant. Now that Trump has taken the lion’s share of delegates in almost every nomination contest and is leading in Florida polls going into Tuesday’s vote, establishment Republicans are frantically burning through money in an effort to reverse his momentum. The chart below, of the cumulative spending by political action committees to attack Trump over time, based on data from the Federal Election Commission, shows them blowing through $24 million since the Iowa caucus, with $12 million of that coming after Super Tuesday. (One caveat: PACs don’t technically need to report expenditures below $10,000 although many do to play it safe with confusing federal electioneering laws.)

Almost all of the money was spent by super PACs, which can accept limitless donations from virtually anyone and spend unlimited amounts on political advertising, as long as they do not coordinate with a campaign. Leading the anti-Trump charge is Our Principles PAC, founded by Republican strategist Katie Packer in January with the stated purpose of preventing Donald Trump from “hijacking our great Party” and assuring that nobody has stopped him yet because “no one has really tried.” It has spent about $9 million. Also taking out its knives: Club for Growth Action, a PAC that raises money from wealthy Republican donors and often supports Tea Party challengers, which has spent more than $6 million against Trump; Conservative Solutions PAC, run by Marco Rubio supporters, nearly $5 million; American Future Fund, a political nonprofit tied to the Koch brothers, about $4 million; anti-tax think tank Club for Growth, $2 million; and the pro-Cruz Stand for Truth, $1.6 million.

Is this negative spending spree hurting Trump? We’ll know more after Tuesday night’s results, but so far it’s not looking like it. He continues to poll better than his rivals nationally and in several of the states voting Tuesday, Illinois, North Carolina, and Florida. Between Trump’s rise and Jeb Bush’s fail is a cruel irony: In an election season in which candidates from both parties have decried the influence of money in politics, the rich who are pouring their money into super PACs don’t seem to be getting much bang for their buck.

Read more Slate coverage of the GOP primary.