The main super-PAC backing Hillary ClintonHillary Diane Rodham ClintonGrassley blasts Democrats over unwillingness to probe Clinton GOP lawmakers cite new allegations of political bias in FBI Top intel Dem: Trump Jr. refused to answer questions about Trump Tower discussions with father MORE's Democratic presidential bid is out with a new six-figure digital ad buy in Iowa that slaps back at the mounting spending by GOP groups to derail her campaign.

The new ad is in direct response to a new Iowa ad from the Karl Rove-backed American Crossroads group bashing Clinton's ties to Wall Street, a line of recent criticism she's faced from Bernie SandersBernard (Bernie) SandersSchumer: Franken should resign Franken resignation could upend Minnesota races Avalanche of Democratic senators say Franken should resign MORE on the debate stage.

Guy Cecil, the chief strategist at the pro-Clinton Priorities USA super-PAC, accused the GOP of trying to tip the scales out of fear Clinton's White House bid.

“Karl Rove and the Republicans are trying to interfere in the Iowa Democratic caucus because they don’t want to run against Hillary Clinton in November. We're not going to let that stand," he said.

“The Republicans know Hillary Clinton is the only one strong enough to stop Wall Street abuse, stand up to the NRA, and protect Planned Parenthood and a women’s right to choose, and Iowans need to know why they’re so afraid of Hillary.” 

The Republican Party and outside groups even lauded Sanders during Sunday's debate and came to his defense from Clinton attacks with emails to reporters. A statement from America Rising on debate night panned Clinton's performance while noting that "everyone is talking about how well Bernie Sanders, her chief rival, did." And the Republican National Committee sent out emails panning "Clinton's misleading health care attack" against Sanders, as well as an email at the end of the contest repeating calls of a "Sanders blowout."

Ian Prior, American Crossroads' spokesman, shot back in a statement to The Hill poking at Clinton's recent comment that she's "flattered" by the group's ad.

"We’re ‘flattered’ that Hillary is so concerned about our ad highlighting her Wall Street hypocrisy that her Super PAC decided to shell out six figures to respond," he said.

"We were already looking forward to facing this underwhelming version of Hillary that needs to deceive voters about her record just to keep pace with her socialist primary opponent - the fact that it's also so easy to push her buttons only raises our excitement."

--This report was updated at 12:45 p.m.