US President Donald Trump will not "survive" the upcoming testimony by his former campaign chairman, Paul Manafort, says former President Barack Obama's ethics chief.

Manafort has pleaded guilty and agreed to cooperate with special counsel Robert Mueller in his investigation into alleged collusion between the Trump campaign and Russia.

"He's not going to survive Manafort's testimony," Norm Eisen told ABC on Sunday. "I think there’s a substantial possibility that this evidence that Manafort is offering will implicate somebody up the chain… Who is up the chain from Paul Manafort, who was the chair of the Trump campaign?"

Former Obama chief ethics lawyer @NormEisen says he believes this is "not the beginning of the end, but the end of the beginning for Donald Trump."



"We have seen the new chapter. He's not going to survive Manafort's testimony," he adds https://t.co/Qtasc7GudN #ThisWeek pic.twitter.com/371R1yMmSm — This Week (@ThisWeekABC) September 16, 2018

Federal charges against Trump’s former campaign chairman include money laundering and lobbying for a pro-Russia group in Ukraine.

"This had absolutely nothing to do with the President or his victorious 2016 Presidential campaign," White House press secretary Sarah Huckabee Sanders said. "It is totally unrelated."

There are also speculations that the Republican president would use his pardoning powers.

"The pardon will only ... hurt Trump," Eisen said. "It will only dig the hole deeper."

Ever since Trump was inaugurated in January 2017, the US intelligence community has overwhelmingly maintained that Moscow sought to meddle in the 2016 election.

Russia has denied meddling in the 2016 election as well as being in possession of any damaging information on the US president.