Donald Trump just renewed his vow of opacity.

Asked by ABC News’s David Muir on Monday afternoon whether he’d be releasing his income-tax returns, as every other major-party presidential nominee has done for 40 years, Trump brushed off the inquiry.

“I think people don’t care,” the GOP nominee declared.

No? A Quinnipiac University poll two weeks ago found that 74 percent of likely voters, including 62 percent of Republicans, think Trump should release his tax returns.

And for those Americans who don’t care, there’s more evidence every day that they should. As Trump was again dismissing the tax-return matter, The Post that afternoon published an extensive report by Dana Priest, Ellen Nakashima and Tom Hamburger laying out what U.S. intelligence officials believe is “a broad covert Russian operation in the United States to sow public distrust in the upcoming presidential election and in U.S. political institutions.”

Democratic presidential nominee Hillary Clinton attacked Republican nominee Donald Trump for not releasing his tax returns during a question-and-answer session on her campaign plane on Sept. 6. (Peter Stevenson/The Washington Post)

If Vladimir Putin’s government — widely believed to be behind cyberattacks on the Democratic National Committee and state election operations — has this “ambitious” plan to influence the election, it stands to reason that Putin would also like to influence the candidates. Trump and his advisers have taken a strikingly pro-Putin line, and Trump and his advisers also have had extensive financial ties to Russia. There’s one sure way to know how beholden Trump is to Putin’s regime: release his tax returns.

This doesn’t mean Trump is some sort of Manchurian Candidate in cahoots with Putin. But it’s bad enough if a President Trump were to feel pressure to tilt in Russia’s favor because he was indebted to Putin-allied investors. Trump dismisses the possibility as nonsense — so why won’t he come clean with his taxes?

The potential for such conflict is a big reason it’s routine for nominees to release their returns. Hillary Clinton has released almost 40 years’ worth, Tim Kaine has released 10, and Mike Pence said he’ll release his this week.

When Trump says nobody cares about the release of his tax returns, he’s forgetting a long list of Republicans — including Rep. Jason Chaffetz of Utah, chairman of the main House investigative panel, Senate Majority Leader Mitch McConnell, Sens. John Barrasso, Ted Cruz and Marco Rubio, and Reps. Sean Duffy and Mark Sanford — have called for Trump to disclose. Mitt Romney, the last Republican nominee, called Trump’s refusal “disqualifying” and speculated that the returns could contain a “bombshell.”

Much has been made of Clinton’s allergy to transparency, and I don’t excuse her obsessive secrecy over her emails and her nearly 280 days without a news conference. (She took questions aboard her plane Monday and Tuesday, a welcome change.) Clinton and Trump should both release more medical information.

But when it comes to transparency, Trump is by far the biggest offender. He’s still banning The Post and other news organizations he doesn’t like. Clinton released the names of her top money-raising “bundlers”; Trump refuses. Clinton has said the Clinton Foundation would stop taking foreign and corporate contributions if she were elected (she should go further, by severing all family ties with the foundation) while Trump has no plans to minimize such conflicts of interest — or even to disclose them.

Trump’s excuse, that he’s waiting for audits to end, has no legal justification. His own accountants have said his audits from 2002 to 2008 have been “closed,” yet his returns from those years remain unreleased.

Do the unreleased returns illustrate shady connections? The Wall Street Journal reported last week that Trump’s real estate investments “brought the GOP nominee into regular contact with people who had ties to organized crime.” Do they show (as earlier returns did) that he paid little or nothing in taxes? Do they confirm reporting by The Post’s David A. Fahrenthold that Trump has been stingy with charities?

Very likely, they would show that Trump has a great deal of debt owned by foreign interests that don’t necessarily share his America First views. The New York Times reported recently that companies directly owned by Trump hold at least $650 million in debt — twice the amount that could be found from his campaign disclosures — and much of Trump’s wealth is in three investments that owe an additional $2 billion.

Wealthy candidates running for high office typically promise to put their investments in a “blind trust” so they can avoid conflicts of interest by not controlling, or even knowing about, their financial interests. But Trump has no plan to do that; he says he’ll have his children run the business while he runs the country.

By refusing to disclose his financial obligations, and by declining to remove any potential conflicts of interest he has with Putin and other foreign entities, Trump has come up with a different notion of blind trust: He wants us to trust him, blindly.

Twitter: @Milbank

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