Russia investigation: Rick Gates' testimony could be 'the end' of the Trump Presidency, says Watergate lawyer

​The decision by former Trump campaign official Rick Gates to plead guilty to federal charges, could mark the end of Donald Trump’s presidency, a veteran lawyer involved in the Watergate scandal has claimed.

John Dean, 79, who served as counsel to President Richard Nixon from July 1970 until April 1973 and who pleaded guilty to a single charge in exchange for acting as a key witness for Watergate prosecutors, said the decision by Mr Gates could be crucial.

“Mueller is throwing everything he can against Manafort, including Gates who can nail him. Increasingly it appears Manafort is the link to Russian collusion,” Mr Dean tweeted

“If Gates can testify that Manafort was acting with Trump’s blessings, it’s the end of his presidency. That’s substantial.”

Gates, 45, who served as a deputy to Mr Trump’s campaign manager, Paul Manafort, pleaded guilty last week as part of a deal with Robert Mueller in the special counsel's investigation into Russia’s alleged interference in the 2016 election.

He pleaded guilty on two federal charges brought by Mr Mueller’s team - one count of conspiracy against the United States and one count of making false statements to FBI agents.

As part of the plea deal, Gates agreed to cooperate “fully, truthfully, completely, and forthrightly”, with the special counsel’s office as well as other law enforcement officials, according to court documents.

Speculation had mounted recently that Gates would plead guilty and cooperate in Mr Mueller’s probe, making him a key witness who could testify in the criminal case against Mr Manafort.

Dean said in a subsequent tweet that people have “expressed concern in this Manafort thread that Trump will pardon him”.

He said: “Many of the counts in both the VA and DC indictments have state law counterparts that can be charged in NY and VA, where Trump had no pardon power. Checkmate is coming for Paul Manafort.“

Mr Manafort has pleaded not guilty to more than a dozen charges, that include money laundering and conspiracy.

Two weeks ago, Mr Mueller indicted 13 Russians on charges relating to a carefully planned scheme to incite political discord in the US in the months before the election.