Outgoing Secretary of State Rex Tillerson struggled for months to secure the nomination of the State Department’s top Asia official, who hawks have accused of being too soft on China. Now that Tillerson is leaving, many inside the administration and in Congress want his potential successor, CIA Director Mike Pompeo, to choose a new nominee to lead U.S. diplomacy in Asia.

Foreign service officer Susan Thornton has been serving as the assistant secretary for East Asian and Pacific affairs for more than a year — a position with broad influence over U.S. relationships with 31 Asian governments — and she has been under attack inside the administration the entire time. Former White House chief strategist Stephen K. Bannon told the American Prospect that Thornton was too weak on China, and that he was working to prevent her nomination.

“I’m getting hawks in. I’m getting Susan Thornton out at State,” he said last August. But he ended up getting fired first.

On Air Force One in November, on the way back from President Trump’s trip to Asia, Tillerson personally persuaded Trump to approve Thornton’s nomination. The White House announced the nomination in December, and Tillerson’s staff said the move was an affirmation of the value of professional diplomats.

But now that that Tillerson is out, Thornton’s detractors want Pompeo to pull her nomination and choose someone else.

“I will not be supporting the nomination of Susan Thornton,” Sen. Marco Rubio (R-Fla.), a member of the Foreign Relations Committee, told me. “During her time at the State Department, she has undermined our strategic allies like Taiwan and downplayed China’s human rights abuses and its export of authoritarianism, favoring smooth bilateral relations with Beijing over ‎a relationship grounded in reciprocity and reality.”

Rubio is expected to place a hold on Thornton’s nomination if and when it his approved by the committee. It would not scuttle the nomination outright, but it could delay it long enough for Pompeo to take over at Foggy Bottom and make his own evaluation.

“I am hopeful that once Mike Pompeo is confirmed he will ask the President to nominate someone who understands the long-term threat posed by China,” Rubio said.

The Florida senator is not alone in his concerns. Several Republican congressional aides and Trump administration officials told me that Thornton, despite being an experienced foreign service officer, is a bad fit on an Asia team that is increasingly hawkish on China. Additionally, Thornton and Mark Lambert, the director for Korea policy at the State Department, have taken over the North Korea portfolio following the retirement of Joseph Yun. Since Pompeo could have a key role in preparing for a potential Trump summit with North Korean leader Kim Jong Un, he may want his own choice to help manage that effort.

Throughout the early days of the administration’s review of China policy and the National Security Strategy process, Thornton was seen as prioritizing continuity in U.S.-China relations over challenging Beijing’s increasingly aggressive behavior around the world.

“On every tactical question of consequence on Asia since the inauguration, Susan has been opposed to taking serious action to counter Chinese economic and political aggression,” a senior White House official told me.

Thornton and her defenders dispute this characterization, though the State Department declined to comment for this article. This dynamic was on display during her February confirmation hearing, during which Rubio pressed her on some specific instances.

For example, the Wall Street Journal reported last October that the State Department resisted efforts by the FBI to arrest officials from China’s ministry of state security who had traveled to New York under false pretenses to pressure Guo Wengui, an exiled Chinese businessman, to stop criticizing the Chinese Communist government.

Thornton initially testified she was “not sure” she was involved in the incident, but responded to follow-up questions from Rubio by saying she was out of the country, and that one of her deputies participated in the process. She did not answer directly whether her office argued against the FBI’s request to arrest the Chinese officials, as the Journal reported.

Rubio also pressed Thornton on why Taiwan’s flag was removed from the State Department website. Thornton testified that the Consular Affairs bureau updated the site without consulting her bureau. In response to follow-up questions, she added that her own bureau had also removed the flag from its website, but defended the decision as being consistent with U.S. policy on Taiwan.

Thornton also declined to specify her role in the State Department’s decision not to sign a February 2017 letter — which was signed by 11 other countries — criticizing the Chinese government for torturing human-rights activists. Thornton said she was “firmly committed to opposing torture and other human rights violations and abuses in China and elsewhere.”

Concerns about Thornton extend beyond China policy, as well. Two administration officials said she worked behind the scenes to slow both U.S. and international efforts to condemn the ethnic cleansing of the Rohingya by the Burmese military during the first months of the atrocities.

Agreeing with Rubio and others, Thornton affirmed in her testimony and written responses that the U.S.-China relationship is out of balance, that the U.S. government should confront China on a range of behaviors, and that she supports the view that China is a strategic competitor with the United States, as Trump administration strategy documents state.

Regardless, calls for withdrawing her nomination are likely to grow louder. Once he’s confirmed, Pompeo will need an Asia team that is trusted by the White House and can be quickly confirmed. Thornton’s prospects for leading that team may follow Tillerson out the door.