U.S. House Republicans have launched a probe into Gov. Tim Walz's longtime ties to China, as his past working with the country that has had a shaky relationship with the U.S. has come into focus now that he's Kamala Harris' vice president pick.

Rep. James Comer, R-Ky., who chairs the House Oversight Committee, called on FBI Director Christopher Wray to investigate Walz's ties in a letter, asking the agency to provide "all documents and communications in the FBI's possession" that would shed light on Chinese entities or individuals Walz may have "engaged or partnered" with.

"It has come to the Committee's attention that Governor Walz has longstanding connections to CCP-connected entities and officials that make him susceptible to the Party's strategy of elite capture, which seeks to co-opt influential figures in elite political, cultural, and academic circles to influence the United States to the benefit of the communist regime and the detriment of Americans," Comer's letter read.

The Oversight Committee chairman argued that Walz's extensive ties to China "raises questions about possible CCP influence in his decision-making as governor—and, should he be elected, as vice president."

Republicans began doubling down on anti-China messaging during the pandemic and Walz's ties to the country have led to fresh GOP attacks.

Walz's relationship with China began in 1989, when he moved there to teach English as one of the country's first U.S.-sanctioned educators. He has since visited the country more than 30 times.

As teachers, he and his wife Gwen Walz organized student trips to China in the early 1990s and also spent their honeymoon there.

Walz used his experience as an educator in China to influence U.S.-China policy during his six terms in Congress, often as a critic of the country's human rights abuses.

He sat on the Congressional Executive Commission on China, a group that looks at human rights issues in the country. He also held meetings with high-profile activists from China, Hong Kong and Tibet, including the Tibetan spiritual leader in exile, the Dalai Lama, whom China accuses of being a separatist.

Walz co-sponsored the Hong Kong Human Rights and Democracy Act of 2017, a bill that mandates an annual report on Hong Kong to Congress to determine whether it has enough autonomy from China to justify the U.S. giving it separate treatment.

The FBI said it received the committee's letter but declined to comment.

The Harris-Walz campaign defended the governor's record and relationship with China.

"Republicans are twisting basic facts and desperately lying to distract from the Trump-Vance agenda: praising dictators, and sending American jobs to China. Vice President Harris and Governor Walz will ensure we win the competition with China, and will always stand up for our values and interests in the face of China's threats," Walz's spokesperson Teddy Tschann said in a statement.