Adam Schiff, the top Democrat on the House Intelligence Committee, said Sunday he thinks that there is evidence of collusion and obstruction in the panel's Russia investigation.

“I think there is evidence” of collusion, Schiff told ABC’s “This Week.” “I can't go into the particulars of our closed investigation. But I also think there is also evidence of obstruction.”

President Trump has repeatedly denounced investigations by the FBI and Congress into whether his campaign colluded with Russia during the 2016 White House race.

This week, the president tweeted that the FBI investigation is a “witch hunt” that is shifting focus from his agenda. 

“I'm not prepared to say that there's proof you could take to a jury,” Schiff said Sunday. “But I can say that there is enough that we ought to be investigating.”

A Washington Post story last week, based on anonymous sources, suggested that the FBI’s probe now includes whether Trump obstructed justice by firing FBI Director James Comey.

“The president has not been notified by anyone that he is under investigation,” Jay Sekulow, a member of Trump's legal team, told “Fox News Sunday.” 

Comey had also previously told Trump and Congress that the president is not the focus of the FBI’s Russia investigation.

The Post’s story comes amid growing criticism about Robert Mueller, who leads the FBI’s special counsel, and his decision to select three members to the counsel who made previous donations to top Democrats.

“The reality is that members of Congress on both sides of the aisle find Mr. Mueller to be a man of incredible integrity and courage who served his country with bravery in Vietnam, who served presidents of both parties, and it's going to take a lot more than a few presidential tweets, or Newt Gingrich, to try to smear this very good man,” Schiff said.

Some of Trump’s allies have called for the firing of Mueller. And people close to the president have said that he is considering it, though Republicans and Democrats alike have urged against doing so.

“The president wants to take down Bob Mueller,” Schiff said. “His lawyer wants to take down Bob Mueller, and the question is why?”

He also told ABC News that he believes that president is targeting Mueller to discredit the findings of his investigation.

The investigation continues “for a good reason,” Schiff said.