Republican presidential candidate Ted Cruz said Tuesday that GOP rival Donald Trump is free to file a "frivolous" lawsuit regarding the Texas senator's eligibility to run for the White House, but he "won't prevail."

"Listen, Donald has been litigious for many, many years. He uses lawsuits to try to intimidate people and attack people," Cruz told conservative talk radio host Hugh Hewitt, The Hill reported. "If he wants to file a frivolous lawsuit, he can file a frivolous lawsuit."

Trump has claimed in recent months that Cruz is not eligible for the presidency because he was born in Canada -- a claim that Cruz has rejected because his mother was an American citizen at the time of his birth.

However, Trump escalated his attack on Monday, calling the Texas senator "unstable" and threatening him with legal action on the matter, according to The Washington Post. The billionaire businessman also called on the Republican National Committee to "intervene" in the matter.

"Ted Cruz is a totally unstable individual," said Trump in a statement. "He is the single biggest liar I've ever come across, in politics or otherwise, and I have seen some of the best of them. His statements are totally untrue and completely outrageous."

However, Trump was not threatening a lawsuit over Cruz's words, but rather his citizenship -- a question that has routinely been raised in recent months.

"One of the ways I can fight back is to bring a lawsuit against him relative to the fact that he was born in Canada and, therefore, cannot be President," said Trump, according to Business Insider. "If he doesn't take down his false ads and retract his lies, I will do so immediately. Additionally, the RNC should intervene and if they don't they are in default of their pledge to me."

Cruz, however, appeared less optimistic that the situation could be resolved. "I think the lawsuit would be frivolous, and he's not going to prevail," Cruz said. "But sadly, whether a lawsuit is frivolous or not has not historically dissuaded Donald Trump from hiring plaintiff lawyers to go to court."