Donald J. Trump is the world’s most powerful man.

As president of the United States, he has at his disposal the ability to put all this Russia/wiretap tumult to rest immediately.

How does he do that if what he says is true, that all this hubbub is much ado about nothing, that it’s all “fake news”?

He can order every aide with any possible tie to the Russia story to talk to congressional investigators. He can order them to speak candidly to the FBI. He can allow the former acting attorney general, the one he fired, to testify before the House Intelligence Committee.

All of this, of course, presumes that Trump is innocent of the accusations that are flying all over Washington, D.C.

Did his campaign conspire with Russian hackers to influence the 2016 election? Trump says it didn’t happen. His behavior of late, however, is beginning to smell like something different. It’s beginning to develop the odor of a cover-up.

House Intelligence Committee Chairman Devin Nunes is pushing back on calls for him to recuse himself from this investigation. Democrats want him out; so do some Republicans. He says he has nothing to hide. Yet he canceled a hearing with former acting AG Sally Yates. It’s fair to ask: Why?

The House investigation is showing symptoms of an impending implosion.

The principal at the center of all this now occupies the White House. This is Donald Trump’s controversy to squash. He can demand a full public accounting of all the questions that are threatening to swallow his still-young presidency.

That presumes the president’s innocence.

Does he — or doesn’t he — have anything to hide?