Top House Intelligence member 'can't comment' if Trump under investigation in Russia probe "I can't answer that one way or the other," Schiff said.

 -- The House Intelligence Committee's top Democratic member said he "can't answer" whether President Donald Trump is under investigation in special counsel Robert Mueller's Russia probe.

"I can't answer that one way or the other," Democratic Rep. Adam Schiff of California told ABC News Chief Anchor George Stephanopoulos on "This Week" Sunday.

Stephanopoulos pressed, "You wouldn't know whether Robert Mueller is investigating the president?"

"I can't comment on that at all," Schiff said.

The House Intelligence Committee is investigating Russia's alleged interference in the 2016 presidential election and possible collusion between Russian officials and the Trump campaign. The Senate Intelligence Committee and special counsel Robert Mueller are also leading their own investigations.

Asked if the House Intelligence Committee’s investigation had become a “side show” because of partisan differences, Schiff said he believed the committee’s Republican chair, Rep. Devin Nunes, has “created serious obstacles.”

“It's not a side show. And we continue the hard work of getting to the bottom of what happened,” Schiff said. “We face serious obstacles, and many of them go back to our chairman, who, I think, all too often, has been willing to further the work and the viewpoint of the White House irrespective of what we're finding in the investigation. That unhelpful.”

“But nonetheless, there are plenty of us Democrats and Republicans that continue to interview the key witnesses, review the key documents, and make progress in the investigation,” Schiff added. “It is still my hope that notwithstanding all the turbulence created at the top of our committee that we can come to a common conclusion.”

Schiff also weighed in on the possibility of the president issuing pardons, saying he doesn't believe Trump's pardon power is as "absolute as people have been suggesting."

"The president cannot pardon people if it's an effort to obstruct justice, if it's an effort to prevent Bob Mueller [or] others from learning about the president's own conduct," the California Democrat said. "I don't think [the president's pardon power] is unlimited, and I think it would be highly problematic for the president if it's part of an effort to obstruct justice."

Schiff added that the president's controversial pardon of former Arizona Sheriff Joe Arpaio suggests Trump may not wait until an investigation is complete to pardon someone.

"The Arpaio pardon was a horrible precedent because that case wasn't even finished," Schiff said. "The president was essentially sending a message, 'I won't even wait until the criminal cases are over to give a pardon.'"