EXCLUSIVE: The battle of the senators is back in full force. 

Texas Sen. Ted Cruz's presidential campaign is releasing a tough new TV ad in South Carolina that targets rival Sen. Marco Rubio on the contentious issue of illegal immigration – featuring people at a faux “self help” session lamenting their past support of the Florida senator.

The 30-second commercial is part of a six-figure ad buy in the Palmetto State ahead of the Feb. 20 Republican primary.

The ad, titled "Self Help," mimics a 12-step group setting, showing people sitting in a circle of folding chairs in a dark room.

"I voted for a guy who was a Tea Party hero on the campaign trail then he went to D.C. and played patty cake with Chuck Schumer and cut a deal on amnesty," one of the participants tells the group.

The group moderator asks him: "Does that make you angry?"

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"Angry? No it makes me feel dumb for trusting him," the middle-aged man says.

"Maybe you should vote for more than just a pretty face next time," another member of the group says.

Right then, a man walks into the room wearing a Rubio-for-president shirt.

"You guys got room for one more?"

The Cruz campaign is also releasing a new website along with the ad called conservativesanonymous.org. 

Asked for comment on the ad, Rubio suggested Cruz is the one who has disappointed voters.

Speaking with Fox News, Rubio accused the Texas senator of changing positions on legalization and other issues, adding: “He's willing to say or do anything to win an election.”

“He portrays himself as some sort of immigration purist. The bottom line is when immigration reform was being debated in Washington, Ted Cruz was a passionate spokesperson on behalf of legalizing people that are in this country illegally, so he either wasn't telling the truth then or he isn't telling the truth now,” he said. 

Fox News' Dan Gallo contributed to this report.