Donald Trump has told Joe Biden to give his "warmest regards" to Vladimir Putin and not fall asleep at the US-Russian summit in Geneva next week.
In a statement issued by his Save America campaign, Mr Trump also said he would trust Russia over "sleezebags" and "lowlifes" the US intelligence agencies, and claimed that his 2018 summit with Mr Putin in Helsinki helped win Washington Moscow's respect.
"Despite the belated Fake News portrayal of the meeting, the United States won much, including the respect of President Putin and Russia," he said of his "productive" meeting with Mr Putin in the Finnish capital.
"Because of the phony Russia, Russia, Russia Hoax, made-up and paid for by the Democrats and Crooked Hillary Clinton, the United States was put at a disadvantage—a disadvantage that was nevertheless overcome by me."
Mr Trump caused consternation following the 2018 summit when he sided with Mr Putin when asked whether Moscow had interfered in the 2016 presidential election.
The White House later claimed that he misspoke.
But he said in his statement on Thursday night:
"As to who do I trust, they asked, Russia or our “Intelligence” from the Obama era, meaning people like Comey, McCabe, the two lovers, Brennan, Clapper, and numerous other sleezebags, or Russia, the answer, after all that has been found out and written, should be obvious."
"Our government has rarely had such lowlifes as these working for it. Good luck to Biden in dealing with President Putin—don’t fall asleep during the meeting, and please give him my warmest regards!"
James Comey was the FBI director who Mr Trump fired in 2017.
Andrew McCabe, his successor, authorised an investigation into possible obstruction of justice by President Trump and has said he was concerned the president was working for Russia against American interests.
John Brennan was a director of the CIA who criticised Mr Trump for not taking the threat of Russian interference seriously.
James Clapper was a director of national intelligence under Barack Obama who said he shared Mr McCabe's concerns that Mr Trump might be a "Russian asset."
Mr Biden will meet Mr Putin in Geneva on Thursday.
That talks are likely to be dominated by a string of grievances including alleged Russian interference in US elections, ransomware attacks on US companies by gangs believed to be based in Russia, and Mr Putin's ongoing undeclared war in Ukraine.
Mr Biden has said he wants to demonstrate to Mr Putin that the alliance between the US and Europe is "tight".
Both Russian and American officials have been managing expectations about the meeting, characterising it as an opportunity to establish dialogue rather than actually resolve their differences.
The pair have met several times in the past but this will be their first meeting since Mr Biden became US president.
