John Dean, who served as White House counsel in Richard Nixon's administration, on Wednesday said Attorney General Jeff Sessions' ousting seemed like a planned "murder."

"This seems to be planned like a murder…It is almost impossible not to interpret this any other way, than a fact to undercut Mueller," Dean told CNN.

In his resignation letter, which was undated but made public on Wednesday, Sessions said his departure came at the request of the president.

John Dean, who served as White House counsel in Richard Nixon's administration, on Wednesday said Attorney General Jeff Sessions' ousting seemed like a planned "murder."

Dean, who was intricately involved in the Watergate scandal, said this appears to be a deliberate move to "undercut" Special Counsel Robert Mueller.

"This seems to be planned like a murder…It is almost impossible not to interpret this any other way, than a fact to undercut Mueller," Dean told CNN.

But Dean also said Mueller likely has a contingency plan, which could include sealed indictments.

Dean pleaded guilty to conspiracy to obstruct justice as part of the investigation into Watergate, but he also provided testimony that played a key role in Nixon's ultimate resignation as he faced the prospect of impeachment.

He has been highly critical of President Donald Trump regarding Mueller's investigation into Russian election interference.

In August Dean tweeted, "Nixon, generally very competent, bungled and botched his handling of Watergate. Trump, a total incompetent, is bungling and botching his handling of Russiagate. Fate is never kind to bunglers and/or botchers! Unlike Nixon, however, Trump won’t leave willingly or graciously."

More recently, Dean in a separate tweet said, "Trump's is making the long nightmare of Nixon’s Watergate seem like a brief idyllic daydream."

In his resignation letter, which was undated but made public on Wednesday, Sessions said his departure came at the request of the president.

Trump was frequently critical of Sessions over his handling of the Justice Department, particularly with regards to Sessions' decision to recuse himself from the Russia investigation.

Read more: Jeff Sessions resigns as attorney general at Trump's request

The president said Matthew Whitaker, Sessions' chief of staff, will take over as attorney general on an acting basis. In this capacity, Whitaker assumes supervision over the special counsel and the Russia investigation from Deputy Attorney General Rod Rosenstein.

Whitaker has been vocally critical of Mueller's probe into Russian election interference and his promotion has already sparked discussions on obstruction of justice. There are widespread fears Trump will urge Whitaker to fire Mueller, which would be an extraordinarily controversial move even among many Republicans and has drawn comparisons to Nixon's infamous Saturday night massacre.

Read more: Jeff Sessions' replacement is good news for Trump and bad news for Mueller

Sessions' ousting also comes just a day after the 2018 midterm elections, in which Democrats gained a majority in the House and Republicans expanded on their majority in the Senate.

Trump has already expressed concerns Democrats would use their new position in the House to launch investigations into his administration — including in relation to Russia — and has threatened to take a "war-like posture" if this occurs.