Frustrated House Democrats Pin Their Hopes on Mueller

House Democrats, frustrated by President Trump’s efforts to stonewall their investigations and eager to stoke public anger about the president’s behavior, are pinning their diminishing hopes on Robert S. Mueller III yet again.

They had a plan: dramatize the special counsel’s damning but dense report on national television in their committees, animating his prose with vivid testimony from witnesses who would discuss Mr. Mueller’s findings on Russia’s election interference and Mr. Trump’s possible obstruction of justice.

But so far Mr. Trump and his allies have successfully parried every one of...