Homeland Security Secretary Kirstjen Nielsen said Wednesday that China is engaged in an “unprecedented” influence campaign leading up to the November midterms, in the Trump administration’s latest warning that Beijing is attempting to sway American opinion ahead of the elections.

Nielsen testified before the Senate Homeland Security and Governmental Affairs Committee, ramping up accusations of China’s interference.

“China is absolutely exerting unprecedented effort to influence American opinion,” Nielsen said, while noting that the administration has not seen any evidence that China is directly targeting election infrastructure.

The topic has come up several times in recent weeks, with both President Trump and Vice President Pence sounding the alarm.

While at the United Nations General Assembly last month, Trump accused China of trying to interfere in the Nov. 6 elections, supposedly over the Trump administration’s tough trade policies.

“They do not want me or us to win because I am the first president ever to challenge China on trade,” Trump said at the U.N., noting there was “plenty” of evidence of China’s attempts to influence, including their propaganda efforts.

“I don’t like it when they attack our farmers and I don’t like it when they put out false messages,” Trump said. “But beside that, we learned that they are trying to meddle in our elections and we’re not going to let that happen just as we’re not going to let that happen with Russia.”

Just last week, Pence warned that China had initiated an “unprecedented effort” to influence the 2018 and 2020 elections, also blaming the efforts on the communist nation’s response to Trump administration trade policies.

“The Chinese Communist Party is rewarding or coercing businesses, movie studios, universities, think tanks, scholars, journalists, and local, state, and federal officials,” Pence said in a speech at the Hudson Institute in Washington D.C. “Worst of all, China has initiated an unprecedented effort to influence American public opinion, the 2018 elections, and the environment leading into the 2020 presidential election.”

Pence added: “To put it bluntly, President Trump’s leadership is working, and China wants a different American president.

He said that Chinese officials have tried to persuade business leaders to condemn administration policy, using methods such as denying a business license to a corporation if it didn’t condemn those policies. He also accused China of targeting industries and states that would play an important role in the November midterms and demanding that Hollywood portray China in a positive light, threatening studios and producers with punishment if they don't.

Additionally, Pence warned of the influence by Chinese media outlets, warning that China Radio broadcasts in American cities, while China Global Television Network reached more than 75 million Americans.

“And it gets its marching orders directly from its Communist Party masters,” he said.

Chinese Foreign Minister Wang Yi responded to Trump’s comments last month, saying that China follows a principle of non-interference in other countries’ domestic affairs.

“We did not and will not interfere in any country’s domestic affairs, we refuse to accept any unwarranted accusations against China and we call upon other countries to also observe the purposes of the U.N. Charter and not interfere in other countries’ internal affairs,” he said.

Meanwhile, FBI Director Christopher Wray joined Nielsen in testifying before the Senate panel, answering questions related to last week’s investigation into now-Supreme Court Justice Brett Kavanaugh.

After a bipartisan call for a further FBI investigation into sexual assault and misconduct allegations brought against Kavanaugh which he denied, the White House backed a supplemental background probe.

The bureau completed the probe and delivered a report to the Senate last Thursday. GOP senators who viewed the report said there was no corroborating evidence of the accusations against Kavanaugh, while Democrats complained the probe was too limited. Kavanaugh was confirmed on Saturday, and sworn in as the newest associate justice of the Supreme Court on Monday evening.

But Wednesday, Sen. Kamala Harris, D-Calif., pressed Wray over whether the bureau was given “full discretion” to investigate.

“Our investigation, our supplemental update, was limited in scope, and that is consistent with this type of case,” Wray said, noting that the communications from the White House went through the bureau’s security division, which has “background investigation specialists.”

“I’ve spoken with them, and they assured me this was handled in a way that was consistent with their experiences,” Wray said. “As standard, the investigation was very specific, limited in scope, and that is the usual process.”

Harris further asked if the FBI investigated whether Kavanaugh lied to Congress.

“That’s not something I can discuss,” Wray said.

Fox News' Adam Shaw and The Associated Press contributed to this report.