WEBSTER CITY, Iowa -- Sen. Ted Cruz (R-Texas) says he thinks John McCain questioning his citizenship is an indication that the political establishment is in "full panic mode," and that the Arizona Republican senator's real motivation is that he secretly supports Marco Rubio for the Republican nomination.

"I think there's no doubt that the Washington cartel is in full panic mode," Cruz said, responding to questions from reporters before a town hall in an airplane hangar in Webster City, Iowa. "Everybody knows John McCain is going to endorse Marco Rubio."

The Texas senator's comments came after McCain said it's "worth looking into" whether Cruz is eligible to be the Republican presidential nominee since he was born in Canada. In an interview with a Phoenix CBS affiliate on Wednesday, McCain said questions raised by GOP front-runner Donald Trump over Cruz's eligibility are plausible.

"I think there is a question," McCain explained in the interview. "I'm not a constitutional scholar on that, but I think it's worth looking into. I don't think it's illegitimate to look into."

McCain has not yet endorsed Rubio in the 2016 race; Sen. Lindsey Graham (R-S.C.), who he previously endorsed, dropped out late last month.

Cruz says he anticipates Rubio will get an endorsement from McCain, which is why McCain brought up his birthplace as a potential stumbling block.

"Their foreign policies are almost identical. Their immigration policies are identical," Cruz continued. "So it's no surprise that people who are supporting other candidates in this race are going to jump on the silly attacks that occur as we get closer and closer to this election."

Trump, who originally raised questions about Cruz's Canadian birth, continued to slam Cruz on Twitter on Thursday, pointing to McCain's recent comments.

"It was a very wise move that Ted Cruz renounced his Canadian citizenship," the Republican front-runner tweeted. "Senator John McCain is certainly no friend of Ted."

When Cruz was asked if he would go to court to clarify his natural-born citizenship as Trump suggested on Wednesday that he do, Cruz smirked before responding.

"No, it's not going to happen," Cruz said. "I won't be taking legal advice anytime soon from Donald Trump. My response when Donald tossed this attack out there was to simply tweet out a video of Fonzie from Happy Days jumping a shark and to move on."

Cruz has slowly risen to the top of the polls in the Hawkeye State, and he says these attacks are a result of his front-runner status there.

"This is the silly season of politics," Cruz said. "Three weeks ago every Republican was talking about Donald Trump. Today, just about every Republican in the field is attacking me."

Cruz also blamed the recent attacks on the mainstream media, something he mentions at every campaign stop, joking that members of the press will be "checking themselves into therapy" after he becomes president.

"With all due respect to our friends in the news media, elections are not won in newsrooms in Manhattan and D.C.," Cruz said to dozens of assembled media outlets on Thursday afternoon. "They are won talking to voters one on one. Answering their questions, their hard questions, not through a whole army of press surrogates who protect a candidate."