– Democrats in Congress will subpoena the full report of special counsel Robert Mueller if the Justice Department only discloses certain parts of it, Sen. Richard Blumenthal said Thursday.

The Connecticut Democrat is a key member of the Senate Judiciary Committee. Republican Sen. Lindsey Graham of South Carolina is the committee's chairman, and the panel has subpoena power over the Justice Department.

CNN reported Wednesday that Mueller could issue a report on Russian interference in the 2016 U.S. elections as early as next week, though the special counsel's notoriously tight-lipped office has provided no timeline for its plans.

Newly confirmed Attorney General William Barr was noncommittal in his confirmation hearing about whether he would allow Mueller to testify before Congress, and whether he would resist a subpoena for the special counsel's report.

Blumenthal told CNN's "New Day" that he is optimistic Graham would join Democrats in the House in subpoenaing the Mueller report. Democratic Chairman Jerrold Nadler of the House Judiciary Committee has said the full report should be made public.

Shielding most of Mueller's report, and issuing select bits and pieces, would create the "public perception of a coverup," Blumenthal warned.

But could the House and Senate actually enforce a subpoena of Mueller?

"A Senate or House Committee may subpoena anyone. The Department of Justice may resist it," Blumenthal clarified Thursday.