Intelligence agencies stopped updating the House Intelligence Committee about the counterintelligence into President Trump's 2016 campaign after former FBI Director James Comey was fired, Chairman Adam Schiff said on Tuesday.

Ahead of testimony by Attorney General William Barr, Schiff opened up what could be another line of questioning he faces from members of the Senate and House Judiciary committees.

"We were getting periodic counterintelligence briefings up until the point where James Comey was fired," Schiff, D-Calif., said on MSNBC. "At that point, the most significant counterintelligence investigation in recent history went into a black hole and the [Justice] Department and the intelligence community stopped fulfilling their statutory obligation to keep us fully informed of any significant counterintelligence activity.

"So they've been dark now for a year and a half," he added. "And that, I think, violates the statute. We're insisting on getting full answers now."

The FBI's original Russia investigation, which began in July 2016, was later wrapped into special counsel Robert Mueller's inquiry looking into Russian meddling in the 2016 election and possible collusion between Trump's campaign and the Kremlin. Mueller was appointed special counsel by Deputy Attorney General Rod Rosenstein eight days after Trump fired Comey in May 2017.

The House Intelligence Committee is one of a handful of Democrat-controlled panels that have revved up investigations into the president this year. Part of this push is to obtain the findings of the counterintelligence investigation, which Schiff said is supported by ranking member Devin Nunes, R-Calif.

"In a very atypical illustration of bipartisanship vis-a-vis the Russia investigation, Mr. Nunes and I have sent two joint requests now to the Department demanding this information," Schiff said. "We're prepared if necessary to use compulsion to get it. We want Mueller to testify, we want the underlying evidence, we want to make sure we get answers."