President Donald Trump says he has spoken to Attorney General William Barr about tracing the origins of the inquiry that cleared him of colluding with Russia.
The Republican president described the investigation by former FBI director Robert Mueller as “an attempted coup”.
William Barr meanwhile said he believes US authorities did spy on the Trump campaign.
US intelligence officials have previously said they were spying on the Russians, not the Trump campaign.
Speaking to reporters at the White House on April 10, President Trump railed against the Department of Justice inquiry into whether the Trump campaign had conspired with the Kremlin to sway the 2016 election.
The investigation cleared him and his aides of collusion, making no determination on whether they had tried to obstruct justice.
President Trump said: “This was an attempted coup. This was an attempted take-down of a president. And we beat them. We beat them.
“So the Mueller report, when they talk about obstruction we fight back. And do you know why we fight back?
“Because I knew how illegal this whole thing was. It was a scam.
“What I’m most interested in is getting started, hopefully the attorney general, he mentioned it yesterday.
“He’s doing a great job, getting started on going back to the origins of exactly where this all started.
“Because this was an illegal witch hunt, and everybody knew it. And they knew it too. And they got caught. And what they did was treason.”
While President Trump was flying off to Texas, William Barr was appearing before the Senate Appropriations Committee.
The attorney general was asked whether spying occurred on the Trump campaign during the 2016 White House race.
“I think spying did occur,” he said.
“The question is whether it was adequately predicated.
“I’m not suggesting it was not adequately predicated, but I need to explore that.”
William Barr said he did not understand why intelligence officials chose not to warn the Trump campaign that it could be vulnerable to infiltration.
He praised the “outstanding” FBI as a whole, but told the panel: “I think there was probably a failure among the group of leaders.”
He added: “I feel I have an obligation to make sure government power is not abused.”
President Trump and his conservative allies have repeatedly suggested the Obama administration planted a mole in his presidential campaign to undercut his candidacy.
The former Director of National Intelligence James Clapper was asked on ABC in May 2018 if the FBI had indeed snooped on the Trump team.
James Clapper replied: “No, they were not. They were spying on – a term I don’t particularly like – but on what the Russians were doing.
“Trying to understand were the Russians infiltrating, trying to gain access, trying to gain leverage and influence which is what they do.”
The same day in an interview with CNN, James Clapper said: “The objective here was actually to protect the campaign by determining whether the Russians were infiltrating it and attempting to exert influence.”
According to the New York Times last year, the FBI sent an informant, an unnamed US academic who teaches in the UK, to speak to two low-level Trump aides, George Papadopoulos and Carter Page, after the agency became suspicious of the pair’s Russian contacts.