All eyes were on former special counsel Robert Mueller as he testified before two congressional committees Wednesday, with members of Congress from both sides of the aisle chiming in on Mueller’s testimony.

Absent among them was U.S. Senator Cory Gardner (R-CO). Throughout both hearings and afterwards, the senator was silent on social media and elsewhere.

The morning hearing focused on Mueller’s findings on possible obstruction of justice by President Donald Trump. During that hearing, Mueller reiterated multiple times that Department of Justice guidance prevented the special counsel’s office from pursuing an indictment against a sitting president.

In an exchange with U.S. Rep. Ken Buck (R-CO), Mueller acknowledged Trump could be indicted for obstruction of justice after he leaves office.

Gardner has yet to comment with any depth on the obstruction of justice charges. He’s previously shrugged at Trump’s possible obstruction, essentially saying the charges don’t matter and that Democrats’ interest was only to “pursue impeachment because they are — you know, I’ve said this before — the House majority is a revenge majority.”

Gardner’s office did not respond to queries as to whether the senator had watched or followed the hearings or if he had read the full Mueller report.

The afternoon portion of the hearing zeroed in on the Russian attempts to influence the 2016 election. Gardner had previously acknowledged that “the report also confirms what we already know, Russia interfered in our election.”

Gardner, speaking to Politico in April remarked,“[T]his is a fair report. And I’m not going to criticize Bob Mueller for the report.”

Former federal prosecutor John Walsh, one of Gardner’s Democratic opponents, criticized Gardner’s silence on Mueller’s testimony.

“Cory Gardner’s silence on these issues, as on so many others, reflects a choice–a choice not to exercise his constitutional responsibilities as senator to check this president,” Walsh told the Colorado Times Recorder.

State Sen. Angela Williams (D-Denver), who’s also challenging Gardner, called on Gardner to hold Trump accountable.

“For far too long, Cory Gardner has sat idly by as the president tramples all over the constitution, and hasn’t lifted a finger to make sure our elections are secure,” said Williams in a statement. “Colorado deserves a U.S. senator who will hold the president accountable, and protect the integrity of our elections.”

Mueller appeared before the U.S. House Judiciary Committee this morning, followed by the House Intelligence Committee.