John Dean, who served as White House counsel during the Watergate scandal that ended Richard Nixon's presidency, is slated to testify next week at the confirmation hearing for Supreme Court nominee Brett Kavanaugh.

The Senate Judiciary Committee announced Dean's addition to the list of expected witnesses on Thursday, two days after releasing an initial list of witnesses including former Secretary of State Condoleezza Rice and Ohio Sen. Rob Portman Robert (Rob) Jones PortmanMcConnell locks down key GOP votes in Supreme Court fight Romney undecided on authorizing subpoenas for GOP Obama-era probes Congress needs to prioritize government digital service delivery MORE (R), who are both set to testify on Kavanaugh's behalf.

Dean is among more than a dozen witnesses selected by Democrats on the Judiciary Committee. The former White House counsel "will speak about the abuse of executive power" during his appearance, according to Sen. Dianne Feinstein Dianne Emiel FeinsteinTrump faces tricky choice on Supreme Court pick The Hill's Morning Report - Sponsored by Facebook - Trump previews SCOTUS nominee as 'totally brilliant' Abortion stirs GOP tensions in Supreme Court fight MORE (Calif.), the top Democrat on the panel.

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Kavanaugh, who was nominated by President Trump Donald John TrumpSteele Dossier sub-source was subject of FBI counterintelligence probe Pelosi slams Trump executive order on pre-existing conditions: It 'isn't worth the paper it's signed on' Trump 'no longer angry' at Romney because of Supreme Court stance MORE in June to succeed retiring Justice Anthony Kennedy, faces a tough confirmation battle in the Senate amid questions over his views on whether a president can be investigated by a special counsel or held liable for criminal activity.

Dean's appearance at the hearing will likely address those questions specifically, as many have drawn parallels between the ongoing special counsel investigation headed by Robert Mueller Robert (Bob) MuellerCNN's Toobin warns McCabe is in 'perilous condition' with emboldened Trump CNN anchor rips Trump over Stone while evoking Clinton-Lynch tarmac meeting The Hill's 12:30 Report: New Hampshire fallout MORE probing Russian interference in the 2016 election and the independent counsel investigation led by Archibald Cox during Watergate.

Trump has escalated his attacks on the Mueller probe in recent weeks, which has secured a conviction for former Trump campaign chairman Paul Manafort Paul John ManafortOur Constitution is under attack by Attorney General William Barr Bannon trial date set in alleged border wall scam Conspicuous by their absence from the Republican Convention MORE and a guilty plea from former national security adviser Michael Flynn.

The president's criticism of the probe, coupled with speculation that he may fire Attorney General Jeff Sessions Jefferson (Jeff) Beauregard SessionsRoy Moore sues Alabama over COVID-19 restrictions GOP set to release controversial Biden report Trump's policies on refugees are as simple as ABCs MORE after the midterm elections, has led to increased scrutiny of his Supreme Court nominee.

Some Democrats, including every minority member of the Judiciary Committee, have called for Kavanaugh's hearing to be delayed after Trump's longtime former lawyer Michael Cohen pleaded guilty earlier this month to campaign finance violations and other charges, saying Trump was involved in a hush-money scheme during the 2016 election.

"Given the possibility of criminal wrongdoing by the President, doubts that Judge Kavanaugh believes a president can even be investigated, and the unprecedented lack of transparency regarding this nominee’s record, we should not move forward with hearings on September 4th," Democratic senators wrote last Friday.

Kavanaugh's hearing, which is set for Tuesday, is likely to also address concerns from Democrats over whether he believes Roe V. Wade, the landmark case that legalized a woman's right to an abortion, is settled law or could be revisited by the court.