I want to look for a moment past the Democratic primary presidential debate that’s coming up. My attention at the moment is riveted on an upcoming appearance by Robert Mueller before the U.S. House Judiciary and Select Intelligence committees.

He is going to make public statements before both panels and then will take questions in private. He is going to talk to the nation about the conclusions he reached regarding Donald Trump’s involvement with Russians who attacked  our electoral system during the 2016 presidential campaign.

He concluded that the president’s campaign did not conspire to collude with the Russians who dug up dirt on Hillary Clinton. He also said that despite evidence of obstruction of justice, he declined to issue a formal complaint against the president; he left that resolution up to Congress. He said in that nine-minute statement he read a few weeks ago that rules and policy prohibited him from indicting a “sitting president.”

I heard this notion come from a former federal prosecutor, but I’ll appropriate it here in this blog. I want the former special counsel to answer this question:

If you were not constrained by Office of Legal Counsel rules and prohibitions against indicting a president, would you have indicted Donald Trump on charges that he obstructed justice?

Mueller can answer such an inquiry any number of ways. If he says “no,” that he wouldn’t have indicted the president, well, that statement would stand on its own.

However, were he to provide an answer that stops short of a flat “no,” he well might say something like this, “I will not respond to a hypothetical circumstance. I deal only with what I know.”

Then again, the former FBI director could answer “yes, I would have issued an indictment.” Suppose, though, he demurs with the “hypothetical” non-answer, that opens the door to supposition that he doesn’t want to reveal his desire — under that circumstance — to file a formal complaint against the president of the United States.

You want high political drama in a congressional hearing room? Robert Mueller’s decision to appear before two key House committees in response to a subpoena is about to deliver it.

I am waiting with bated breath.