KIMBERLEY STRASSEL: Obstruction of Congress: Mueller, the Justice Department and the FBI aren’t helping the lawmakers’ probe.

The media echo chamber spent the week speculating about whether Special Counsel Robert Mueller can or will nab President Trump on obstruction-of-justice charges. All the while it continues to ignore Washington’s most obvious obstruction—the coordinated effort to thwart congressional probes of the role law enforcement played in the 2016 election.

The news that senior FBI agent Peter Strzok exchanged anti-Trump, pro-Hillary text messages with another FBI official matters—though we’ve yet to see the content. The bigger scandal is that the Justice Department, the Federal Bureau of Investigation and Mr. Mueller have known about those texts for months and deliberately kept their existence from Congress. The House Intelligence Committee sent document subpoenas and demanded an interview with Mr. Strzok. The Justice Department dodged, and then leaked.

The department also withheld from Congress that another top official, Associate Deputy Attorney General Bruce Ohr, was in contact with ex-spook Christopher Steele and the opposition-research firm Fusion GPS. It has refused to say what role the Steele dossier—Clinton-commissioned oppo research—played in its Trump investigation. It won’t turn over files about its wiretapping.

And Mr. Mueller—who is well aware the House is probing all this, and considered the Strzok texts relevant enough to earn the agent a demotion—nonetheless did not inform Congress about the matter. Why? Perhaps Mr. Mueller feels he’s above being bothered with any other investigation. Or perhaps his team is covering for the FBI and the Justice Department.

Perhaps.