(CNN) Democrats are planning to call John Dean, who served as White House counsel during the Nixon presidency, to testify in opposition to Judge Brett Kavanaugh next week during his Supreme Court confirmation hearings, according to a release Thursday from Senate Judiciary Chairman Chuck Grassley, R-Iowa.

Former Solicitors General Paul Clement and Theodore Olson, who are two of the most successful members of the conservative Supreme Court bar, will be among those testifying in support of Kavanaugh.

Dean, a CNN contributor, is known for his cooperation with prosecutors during the Watergate investigation. Democrats -- seizing on some of Kavanaugh's past statements regarding presidential authority -- hope to highlight Dean's testimony on the abuse of executive power.

In all, 13 witnesses will testify in support of Kavanaugh and 13 will speak against his nomination during a Senate Judiciary Committee hearing September 7 that will focus on the nominee's early career in partisan politics, his years in the George W. Bush White House and the nearly 300 opinions he's issued as a federal judge.

The witnesses' testimony will come after Kavanaugh has spent hours answering questions from both sides of the aisle Wednesday and next Thursday. The witnesses are meant to offer different perspectives on the nominee, and shore up any questions that may have been raised during the hearings.

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