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SENECA, S.C. -- Ted Cruz went all-in on Wednesday in his dash to take down Donald Trump, calling on the frontrunner to follow through on a lawsuit threat against him and testify "under oath under penalty of perjury answering" questions over his stance on abortion rights.

At a 40-minute press conference on Wednesday, Cruz presented reporters a cease-and-desist letter that his campaign received on Tuesday from a lawyer for Trump, a letter Cruz said was “one of the most remarkable letters I’ve ever read.”

Trump’s lawyer demanded that the Cruz campaign stop playing an ad that includes the video clip from a 1999 Meet the Press interview in which Trump said at the time that he was “very pro-choice.”

Cruz repudiated the lawsuit threat on Wednesday, telling reporters that if Trump were to file the lawsuit, both he and his lawyer would face “being sanctioned in court for filing frivolous litigation.”

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“Mr. Trump, you have been threatening frivolous lawsuits for your entire adult life,” Cruz said, addressing the cameras in the room. “Even in the annals of frivolous lawsuits, this takes the cake.

Cruz continued, “So Donald, I would encourage you -- if you want to file a lawsuit challenging this ad, claiming it is defamation, file the lawsuit.”

The former Texas solicitor general then suggested that he looked forward to “deposing Donald Trump” himself, saying, “I may well not use outside counsel.”

Trump’s lawyer, Jeffrey Goldman, wrote in a letter to the Cruz campaign that the ad is “disingenuous” and “replete with outright lies, false, defamatory and destructive statements and downright fabrications.” He said that Cruz’s representation of Trump as pro-choice could not be “further from the truth.”

Cruz laid out his case for why Trump’s claim has no standing, including pointing out Trump’s interview in 1999 when he called himself “very pro-choice” and Trump’s comments at this last weekend’s debate defending Planned Parenthood.

Trump released a statement after Cruz’s remarks, writing that Cruz’s efforts are “clearly desperate moves by a guy who is tanking.”

“If I want to bring a lawsuit it would be legitimate,” Trump wrote. “Likewise, if I want to bring the lawsuit regarding Senator Cruz being a natural born Canadian I will do so. Time will tell, Teddy.”

Cruz’s press conference -- which often seemed more like a courtroom with a lawyer, video clip and poster presentation boards – went beyond the lawyerly back-and-forth over potential lawsuits.

Cruz also looked to implicate Trump for being “a direct cause of Obamacare.”

“Donald Trump is a direct cause of Obamacare passing because if either house had remained in Republican control, Obamacare never would have passed,” Cruz bemoaned as he pointed to a poster board that listed 30 different Democratic politicians and organizations in which Trump had once donated to.