Sen. John McCain appears on CNN's 'State of the Union' with Jake Tapper to discuss the "barrage of conspiracy theories" coming out of the Trump campaign. Tapper asked McCain: "Do you have any concern about the constant barrage of conspiracy theories we keep hearing from the president?" "On an issue such as this, accusing a former president of the United States of doing something which is not only illegal, but just unheard of, then that requires corroboration. And I will let the American people be the judge," McCain replied. <blockquote>TAPPER: Trump made a stunning allegation: He tweeted that President Trump had wiretapped him at Trump Tower during the campaign. On Monday, you said that: "If President Trump has any information that would indicate that his predecessor wiretapped Trump Tower, he should come forward with the information. The American people deserve it." That is your quote. The White House is supposed to hand over any evidence it has to back this charge to the House Intelligence Committee by tomorrow, but a White House official this morning suggesting they might not turn anything over. If there's no proof for what the president said -- and we know that the FBI director has said it is not true, and the former director of national intelligence has said it's not true -- should President Trump take back his charge and apologize to President Obama and to the American people? MCCAIN: Well, look, President Trump has to provide the American people, not just the Intelligence Committee, but the American people, with evidence that his predecessor, former president of the United States, was guilty of breaking the law, because our director of national intelligence, General Clapper, testified that there was absolutely no truth to that allegation. So, I think the president has one of two choices, either retract or to provide the information that the American people deserve, because, if his predecessor violated the law, President Obama violated the law, we have got a serious issue here, to say the least. TAPPER: But there's no one I have heard who has any information relating to the FBI or intelligence, including Vice President Pence, Sean Spicer, Sarah Huckabee Sanders, who has said that they know of any information that backs this up. Do you have any reason to think that this charge is true? MCCAIN: I have no reason to believe that the charge is true. But I also believe that the president of the United States could clear this up in a minute. All he has to do is pick up the phone, call the director of the CIA, director of national intelligence, and say, OK, what happened? Because they certainly should know whether the former president of the United States was wiretapping Trump Tower. TAPPER: Do you have any concern about the constant barrage of conspiracy theories we keep hearing from the president? MCCAIN: Well, the president obviously has a unique style. He was elected president of the United States. And I'm not telling him how he should conduct that presidency. But I do believe that, on an issue such as this, accusing a former president of the United States of doing something which is not only illegal, but just unheard of, then that requires corroboration. And I will let the American people be the judge. But this is serious stuff, Jake, because it under -- if true, or the allegation is left out there, it undermines the confidence the American people have in the entire way that the government does business. </blockquote>