House Oversight and Accountability Committee Chair James Comer (R-Ky.) subpoenaed Homeland Security Secretary Alejandro Mayorkas on Monday for information relating to Minnesota Gov. Tim Walz, the Democratic nominee for vice president, and a vague alleged connection to the Chinese Communist Party (CCP).

Comer said in a letter accompanying the subpoena — issued on the day before the vice presidential debate between Walz and Republican Sen. JD Vance (Ohio) — that his committee received whistleblower disclosures about “serious concern among Department of Homeland Security (DHS) personnel regarding a longstanding connection between” Walz and China. 

Specifically, Comer pointed to a nonclassified chat that DHS employees used on Microsoft Teams titled “NST NFT Bi-Weekly Sync” that he said contains relevant information, in addition to further classified and unclassified documents in the control of DHS. The acronym stands for “Nation State Threat — National Functional Team,” according to the committee.

Comer did not go into detail about what kind of concerns were raised about Walz’s alleged connection to China but said the information came through a whistleblower.

Walz, a former educator, spent a year teaching in China in 1989, and later led field trips to the country — visiting China dozens of times. That travel has been under scrutiny from House Republicans since he ascended to the presidential ticket over the summer.

The subpoena gave a deadline of Oct. 7 to produce the communication in the Microsoft Teams group chat relating to Walz from July 1, 2024, to present, as well as any intelligence information reports or regional intelligence notes since Nov. 2023 to present relating to Walz, his staff, or his gubernatorial office.

It is unusual for committees to issue a demand for documents without first sending a letter requesting the information to be provided voluntarily.

Rep. Jamie Raskin (D-Md.), the ranking member on the committee, dismissed Comer’s subpoena as political.

“What do you know, it’s the eve of the vice-presidential debate, and Chairman Comer has apparently been assigned another flotsam and jetsam errand from the GOP’s political smear barrel,” Raskin said in a statement. “The tarnished hero of the Biden impeachment investigation has just thrown out one of his classic boomerang ‘bombshell’ accusations, revealing to the world that employees at the Department of Homeland Security were actually chatting about Governor Tim Walz over Microsoft Teams message! This comically trivial last-ditch attempt to smear Governor Walz is one more embarrassing and strained attempt to curry favor with Donald Trump’s collapsing campaign.” 

The subpoena is just the latest action from Comer and House Republicans taking greater aim at Walz and Vice President Harris in the wake of President Biden dropping out of the presidential race and Harris becoming the party’s nominee.

The House Education Committee subpoenaed Walz himself earlier this month in relation to a Minnesota nonprofit that had been charged for fraudulently using federal COVID-19 funds.

Rep. Jim Banks (R-Ind.) previously wrote to Defense Secretary Lloyd Austin questioning whether Walz complied with foreign travel reporting requirements for his security clearance as he traveled to China while serving in the National Guard.

And Comer previously sought information from the FBI about whether it has ever offered any defensive briefings to Walz, a practice by which the agency informs politicians and other figures whether they may be a target of Chinese intelligence or influence efforts. Comer also asked the FBI to turn over information on more than a dozen Chinese entities, including some it’s unclear Walz had any contact with.

Comer’s Monday letter, though, aimed to signal that the move to subpoena DHS had motivations other than politics.

“The Committee’s investigation of the CCP — begun long before Governor Walz was elevated to be the vice-presidential candidate for Democratic presidential candidate Kamala Harris — seeks to understand the extent of the CCP’s infiltration and influence campaign and to identify legislative reforms to combat CCP political warfare targeting prominent Americans for elite capture,” Comer said in the letter to Mayorkas. 

“In particular, if a state governor and major political party’s nominee for Vice President of the United States has been a witting or unwitting participant in the CCP’s efforts to weaken our nation, this would strongly suggest that there are alarming weaknesses in the federal government’s effort to defend the United States from the CCP’s political warfare that must be urgently addressed,” Comer added.

The Harris-Walz campaign did not immediately provide comment on the subpoena. DHS declined to comment.

Rebecca Beitsch contributed.

Updated at 6:03 p.m.