Top House Republicans on Monday called on the FBI to brief them on espionage activities by the Chinese Communist Party (CCP) within the United States and to what extent such operations have compromised elected officials without them knowing it.

The letter, signed by Republicans on the House Oversight and Reform Committee, comes after an Axios report said that a suspected Chinese spy named Fang Fang had built relationships with up-and-coming politicians and had gained significant proximity to Rep. Eric Swalwell, D-Calif.

The House Reps. said that CCP activities in the U.S. have “garnered significant results, including interacting with a Member of Congress on the House Intelligence and Judiciary Committees.”

“According to media reports, the CCP intelligence operative known as Fang Fang had developed extensive relationships with elected officials at every level of government, including a Democrat U.S. Congressman,” the Republicans wrote.

The Republican Reps. cited U.S. intelligence officials who say believe Fang’s operation was likely orchestrated by the CCP’s primary civilian spy agency, the Ministry of State Security (MSS), between 2011 and 2015.

The operation, they said, “targeted primarily Democrat politicians in the San Francisco area, but also around the country.”

“Depending on the total number of active CCP operatives and the breadth of the MSS operation across our country, any number of elected officials could potentially be compromised without even knowing it,” the Republicans wrote.

According to the Axios report, Fang first interacted with Swalwell in 2012. He cut ties with her in 2015 after he was briefed by the FBI and she left the U.S. that same year amid an investigation. The San Francisco Chronicle reported that he was not under investigation for any wrongdoing himself.

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Republicans have called on Swalwell to step down from his role on the Intelligence Committee.

In an interview on “The Story” with Martha MacCallum last week, Rep. Elise Stefanik, R-Calif., said Swalwell is “compromised and he needs to step down.”

House Minority Leader Kevin McCarthy, R-Calif., meanwhile, called Swalwell a “national security threat.”

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The Republicans who signed Monday’s letter request that FBI Director Christopher schedule a staff-level briefing on the matter by Dec. 21, 2020.

Fox News' Tyler Olson contributed to this report.