John McCain on Trump's wiretapping claim: Take it back or show us the evidence

Sen. John McCain has weighed in on President Donald Trump's seemingly unfounded wiretapping accusation against former President Barack Obama, stating on CNN's State of the Union that now is the time for Trump either to show his hand, or to take the whole thing back. 

"The president has one of two choices: either retract, or to provide the information that the American people deserve," McCain said on Sunday. 

On March 4, Trump tweeted a bold and apparently baseless allegation that Obama had wiretapped Trump Tower during the 2016 presidential campaign. If true, it would mean Obama violated the law in a big way, McCain explained, so Trump is now obligated to "provide the American people, not just the intelligence committee," with evidence to support his claim. 

So far, though, there is no reason to suspect that Obama did anything wrong. The former president's spokesperson, Kevin Lewis, immediately responded to the assertion, saying it was "simply false." 

Trump's wiretapping theory baffled even his top aides, who reportedly awoke to the president's tweet storm without the faintest idea of what he could've been talking about. As State of the Union host Jake Tapper pointed out in Sunday's interview, Vice President Mike Pence, White House press secretary Sean Spicer and deputy press secretary Sarah Huckabee Sanders have all said they have no evidence to support Trump's claim. 

McCain told Tapper that, if he wanted to, Trump could easily put the matter to bed. 

"All he has to do is pick up the phone, call the director of the CIA, the director of National Intelligence and say, 'Okay, what happened?'" McCain said.

It's far from the first time the Senate Armed Services Committee chairman has been publicly critical of the president and his rash tweeting habits. After Trump used Twitter to label legitimate news outlets, including the New York Times and CNN, "FAKE NEWS," McCain offered a warning on NBC's Meet the Press.

"If you want to preserve — I'm very serious now — if you want to preserve democracy as we know it, you have to have a free and, many times, adversarial press. And without it, I am afraid that we would lose so much of our individual liberties over time. That's how dictators get started."