[citation needed] In 1977, Halper became special counsel to the Congressional Joint Economic Committee and legislative assistant to Senator William Roth (R-Del.).

In connection with his position Halper's name came up in the 1983/4 investigations into the Debategate affair, which was a spying scandal in which Central Intelligence Agency (CIA) officials passed classified information about Carter administration's foreign policy to Reagan campaign officials in order to ensure the Reagan campaign knew of any foreign policy decisions that Carter was considering (Iran hostage crisis).

[12] According to Peter Dale Scott's book The Iran-Contra Connection: Secret Teams and Covert Operations in Reagan Era on the Iran–Contra affair, Ray Cline's son-in-law Roger Fontaine "made at least two visits to Guatemala in 1980 ... (with General Sumner) drafting the May 1980 Santa Fe Statement, which said that World War III was already underway in Central America against the Soviets and that Nicaragua was the enemy.

"[13] The Palmer National Bank, where Halper worked, was described as "the D.C. hub by which Lt. Col. Oliver North sent arms and money to the anti-Sandinista guerrilla Contras in Nicaragua.

He has served on the Advisory Board of Directors of the Paul H. Nitze School of Advanced International Studies and contributed to various magazines, journals, newspapers and media outlets.

These include: The Washington Post, Los Angeles Times, The Wall Street Journal, the BBC, CNN, SKY NEWS, ABC, CBS, NBC, C-Span, and a range of radio outlets.

Halper had been the deputy director of the State Department's Bureau of Political-Military Affairs shortly before taking on the operation research assignment.

Halper was officially a campaign aide responsible for providing 24 hour news updates and policy ideas.

David Prosperi, another Reagan campaign aide, said, "He provided us with wire stories and Carter speeches, but people talked about his having a network that was keeping track of things inside the Government, mostly in relation to the October Surprise."

Ray S. Cline, Halper's then father-in-law and a former senior Central Intelligence official, dismissed the Reagan aides' disclosures as a "romantic fallacy.

[21] A former federal law enforcement official told The New York Times that their initial encounter at a London symposium on July 11–12, 2016 was a coincidence, rather than at the direction of the FBI.

[21] On September 2, 2016, Halper contacted Papadopoulos, inviting him to London and to write a paper on Mediterranean oil fields, which he did.

The Times also reported that the FBI also sent an investigator using the name Azra Turk to meet with Papadopoulos, while posing as Halper's assistant.

Flynn was forced out of the DIA six months later, although public accounts at the time cited other reasons for his removal, including his management style and views on Islam.

Halper's motion to dismiss stated in part: "Private individuals who participate in FBI investigations are subject to the federal common law qualified immunity applicable to government agents.

Spying Axios reported in May 2018 that during the transition Trump top trade advisor Peter Navarro had recommended Halper for an ambassadorship.