U.S. President Donald Trump speaks at the Susan B. Anthony List 11th Annual Campaign for Life Gala at the National Building Museum in Washington, May 22, 2018.
U.S. President Donald Trump speaks at the Susan B. Anthony List 11th Annual Campaign for Life Gala at the National Building Museum in Washington, May 22, 2018.

WASHINGTON - U.S. President Donald Trump on Wednesday called the FBI's use of an informant to talk to three of his 2016 campaign associates "SPYGATE," saying it "could be one of the biggest political scandals in history!"

The U.S. leader said on Twitter, "Look how things have turned around on the Criminal Deep State. They go after Phony Collusion with Russia, a made up Scam, and end up getting caught in a major SPY scandal the likes of which this country may never have seen before! What goes around, comes around!"

As he has done many times, Trump attacked the probe as a "WITCH HUNT!"

Trump's ire was aimed at the Federal Bureau of Investigation's alleged use of Stefan Halper, an American foreign policy scholar at Britain's University of Cambridge, as a secret informant to report on foreign affairs conversations he had with the three Trump advisers — Carter Page, Sam Clovis and George Papadopoulos. Decades ago, Halper served in three Republican U.S. administrations in various domestic policy roles.

The FBI, at the time it used Halper as an informant, was probing Trump campaign links to Russian interests during the latter stages of the 2016 campaign, part of what eventually became special counsel Robert Mueller's ongoing criminal investigation. Papadopoulos has pleaded guilty to lying to investigators about his contacts with Russians.

In recent days,Trump has cited news reports indicating Halper was embedded in his campaign.

Late Tuesday, the U.S. leader said, "If the person placed very early into my campaign wasn't a SPY put there" by the former President Barack Obama's administration's "for political purposes, how come such a seemingly massive amount of money was paid for services rendered - many times higher than normal ..."

It has not been disclosed how much the FBI paid him. But U.S. financial records show that since 2012, Halper has had contracts with the Defense Department for more than $1 million for research and development in the social sciences and humanities, although the money did not go solely to him. He hired other academics to help with the research and prepare reports.

Trump said in another tweet, "Follow the money! The spy was there early in the campaign and yet never reported Collusion with Russia, because there was no Collusion. He was only there to spy for political reasons and to help Crooked Hillary win," Trump's oft-repeated pejorative for his 2016 Democratic challenger, former U.S. Secretary of State Hillary Clinton.

After Trump earlier this week demanded the FBI and its parent agency, the Justice Department, disclose confidential records about the use of Halper, Deputy Attorney General Rod Rosenstein and FBI director Christopher Wray agreed to meet Thursday with two key Republican lawmakers, Congressmen Devin Nunes and Trey Gowdy, to show them the information.

FILE - Deputy Attorney General Rod Rosenstein leav
Deputy Attorney General Rod Rosenstein leaves a meeting at the White House in Washington, May 21, 2018.

Trump told White House reporters he was not "undercutting" the Justice Department by making his demand for the information about Halper.

"We're cleaning everything up. This was a terrible situation," he said. "I want total transparency ... because this issue supersedes Republicans and Democrats." However, Democrats have not been invited to Thursday's briefing.

Trump said he did "a great service to this country" by firing former FBI director James Comey a year ago.  Comey's ouster came at a time when he was leading the Russia investigation, before Mueller, over Trump's objections, was appointed by Rosenstein to take over the probe. 

Rosenstein has also asked the Justice Department's inspector general to investigate the FBI's use of Halper.

"If anyone did infiltrate or surveil participants in a presidential campaign for inappropriate purposes, we need to know about it and take appropriate action," Rosenstein said.