Washington CNN  — 

Despite being backed by the monumental Right to Rise super PAC, Jeb Bush said Monday he would “eliminate” the Supreme Court decision that paved the way for super PACs.

“If I could do it all again I’d eliminate the Supreme Court ruling” Citizens United, Bush told CNN’s Dana Bash. “This is a ridiculous system we have now where you have campaigns that struggle to raise money directly and they can’t be held accountable for the spending of the super PAC that’s their affiliate.”

Not long after Bush made his comments, Donald Trump – who often touts that he is not using a super PAC – mocked Bush on Twitter.

“Now that Bush has wasted $120 million of special interest money on his failed campaign, he says he would end super PACs. Sad!” Trump tweeted.

Bush’s Right to Rise super PAC has dominated the fundraising race, pulling in $117.6 million last year, according to the latest FEC filings. But that money has not been enough to stop Bush’s fall from the front of the Republican pack. And Right to Rise, run by Bush confidant Mike Murphy, has become the subject of derision among Bush supporters.

Opinion: Super PACs a disaster for democracy

In order to counter the court ruling, Bush has said he would seek a constitutional convention, where he would also push for term limits and balanced budget amendment.

But Bush doesn’t want to limit campaign contributions, instead he has said regularly that he wants to lift the cap on direct campaign donations and also disclose who is making those donations.

Despite that position, David Bossie, president of Citizens United, whose group won the landmark court ruling in 2010, accused Bush of siding with liberals.

“Jeb Bush’s true colors just resurfaced,” Bossie said Monday. “He has embraced the left’s view of the First Amendment. Jeb Bush now agrees with Hillary Clinton and Bernie Sanders to limit free speech in America.”

On the other side of the aisle, a liberal campaign money watchdog group said removing the limits on donations would be no better than keeping Citizens United in place.

“If Bush wants to stand out from other GOP candidates on this issue and appeal to voter concerns over money in politics, he should adopt comprehensive solutions to give everyday people a voice in politics,” said David Donnelly president and CEO of Every Voice.

Bush reiterated his comments in a speech Monday afternoon.

“The ideal situation would be to overturn the Supreme Court ruling that allows for … unregulated money for the independent and regulated for the campaign,” the former Florida governor told a Luncheon in Nashua, New Hampshire. “I would turn that on its head if I could.”

Bush has grumbled before about the fundraising demands of the 2016 cycle, but he has sharpened his tone on the trail recently. He cited a mailer from one opponent’s super PAC that attacked his mother, former First Lady Barbara Bush.

Barbara Bush joining Jeb on the campaign trail

“I mean, I just saw a mailing that attacked me through my mother with one of the super PACs,” Bush told CNN. “C’mon man, that’s a pretty low blow.”

A spokesman for Conservative Solutions PAC, which produced the mailer and is supporting Marco Rubio, called it a stretch to say it targeted Jeb Bush’s mother.

“To say these famous monarchs and fast food legends are included to represent real people requires a leap of royal proportions,” said Jeff Sadosky, a Conservative Solutions spokesman.

CNN’s Ashley Killough contributed this report.