Acting Attorney General Matthew Whitaker stands during the playing of the National Anthem at the Department of Justice's Annual Veterans Appreciation Day Ceremony at the Justice Department in Washington, Nov. 15, 2018. Credit: Pablo Martinez Monsivais | AP

Supporters of special counsel Robert Mueller’s investigation of Russian interference in the 2016 presidential election fear that acting attorney general Matthew Whitaker will soon fire Mueller. President Donald Trump, who appointed Whitaker after forcing Jeff Sessions’ resignation on Nov. 7, has denied collusion between his campaign and the Russians, and has repeatedly characterized the Mueller investigation as a “witchhunt.” But a move by Whitaker — a Trump loyalist — to fire Mueller would surely prompt a constitutional crisis, particularly after a Democratic majority takes power in the House in January.

Yet there is another, more insidious threat to the investigation: that Whitaker will curtail it without firing Mueller and that, because of a loophole in the special-counsel regulations, the public would not find out until far too late. On “Fox News Sunday” this past weekend, Trump said he wouldn’t stop Whitaker if he wanted to limit the investigation. “It’s going to be up to him,” Trump said. “I would not get involved.”

The 1999 regulations governing Mueller and his interactions with Justice Department require the attorney general to immediately notify the Democratic and Republican leaders of the judiciary committees in both the House and Senate of a special counsel’s removal.

But no such immediate notification would be required if Whitaker, instead, blocked the special counsel’s plans and tried to shape the investigation.

How would that work? The regulations establish the special counsel’s independence and give him a wide ambit, but they also require him to report — in advance — to the attorney general all significant actions that might be taken. The attorney general, in turn, may request that the special counsel explain a contemplated action, and “may, after review, conclude that the action is so inappropriate or unwarranted under established Departmental practices that it should not be pursued.”

The attorney general is directed to give “great weight” to the special counsel’s views but, otherwise, his discretion to overrule is broad and cannot be appealed.

Here’s the loophole in regulations that would keep Congress from learning about such an overruling in a timely way: The attorney general is required to notify Congress that he had taken the action only “upon conclusion of the Special Counsel’s investigation.”

As special counsel, Mueller is generally forbidden from publicly commenting on his investigation and from communicating with Congress directly, unlike an independent counsel such as Kenneth Starr, who was authorized to prepare a report for Congress and the public about his investigation of President Bill Clinton two decades ago. Mueller is directed to communicate only with the attorney general.

There is no real-time mechanism to compel disclosure of any interactions between Whitaker and Mueller. If the two meet, when they meet, what prospective actions Mueller reports and how Whitaker responds — these steps would be hidden from view. Whitaker and Trump would have no interest in publicizing them, and Mueller is famously tight-lipped, and a rule-follower to boot. He might chafe — but would he violate regulations and department policies by going public?

Yes, someday under the regulations we may learn details of Mueller’s interactions with Whitaker, and of any effort to interfere. Someday Mueller will present a report in which he can outline any way in which his investigation may have been shaped by Whitaker. But that someday will come only when Mueller is ready to close up shop, and the person he’ll tell is the attorney general himself. The attorney general will then weigh the report, operating under no mandated deadline, and eventually make his own notice to Judiciary Committee leaders in each house.

If evidence of Whitaker’s interference emerged, we might then learn how the House Democrats’ new subpoena power could serve as a check on the president. We may even learn the limits of Republican loyalty to the president if he were shown to have hobbled the investigation.

By then, the Mueller investigation would be closed, the prosecutors and FBI agents scattered, the boxes of evidence sent to storage. The inquiry into possible collusion between Russia and the Trump campaign in 2016 would have been successfully thwarted without taking the openly incendiary step of firing the special counsel.

Nelson W. Cunningham served as a federal prosecutor in the Southern District of New York under Rudy Giuliani, as general counsel of the Senate Judiciary Committee under then-chair Joe Biden and as general counsel of the White House Office of Administration under President Bill Clinton.