Acting Homeland Security Secretary Chad Wolf resigned from his post Monday, just days after he pledged to stay in the job until President Donald Trump’s last day in office.

Pete Gaynor, the Federal Emergency Management Agency administrator, will take over as acting secretary, a senior DHS official said.

Wolf said he was “saddened to take this step” because he planned to stay on as acting department chief until Jan. 20.

“Unfortunately, this action is warranted by recent events, including the ongoing and meritless court rulings regarding the validity of my authority as Acting Secretary,” he said in an email to DHS staff. “These events and concerns increasingly serve to divert attention and resources away from the important work of the Department in this critical time of a transition of power.”

Wolf will remain at the department in his Senate-confirmed role as undersecretary for strategy, policy and plans, a department spokesperson said.

Wolf’s departure makes him the third Cabinet-level official to quit following Wednesday’s attack on the U.S. Capitol by a mob of Trump supporters. Transportation Secretary Elaine Chao and Education Secretary Betsy DeVos resigned last week.

Rep. Bennie Thompson, D-Miss., who chairs the Homeland Security Committee, called the timing of Wolf’s resignation “questionable,” noting ongoing concerns about whether he “has been serving illegally in his position.”

“He has chosen to resign during a time of national crisis and when domestic terrorists may be planning additional attacks on our government. Unlike others, he is apparently not leaving the Trump Administration on principle,” Thompson said in a statement. 

“If it is true he is resigning because of recent federal court decisions, then it is an admission that his policy decisions are indeed invalid. Under this scenario, Ken Cuccinelli must also resign,” he said, a reference to Homeland Security’s acting deputy secretary. 

Rep. John Katko, R-N.Y., the ranking member on the Homeland Security committee, praised Wolf’s work. 

“In the toughest of circumstances, Chad Wolf served the nation admirably as the Department of Homeland Security’s Acting Secretary,” he said in a tweet, adding in another post: “He is a true homeland security professional, and for his career of service in numerous senior roles he deserves nothing but our gratitude.”

In a statement last Thursday, Wolf called on the president to condemn the “tragic and sickening” attack on the Capitol, but he also said he planned to remain in his role for the remaining weeks in Trump’s term. Wolf has been a staunch supporter of Trump’s hard-line immigration policies.

Hours after Wolf issued his statement, Trump withdrew his nomination to serve permanently in his role as DHS chief.

[Trump pulls Homeland Security nomination after criticism]

DHS oversees the three immigration agencies — U.S. Citizenship and Immigration Services; Customs and Border Protection; and Immigration and Customs Enforcement. It also oversees the Transportation Security Administration, FEMA, the Secret Service and several other agencies.

Wolf was sworn in as acting secretary in November 2019. He is the fifth person to lead Homeland Security since Trump took office. He stepped into the role following the resignation of Kevin McAleenan, who served as acting secretary. Neither Wolf nor McAleenan was ever confirmed by the Senate.

Wolf’s appointment has been embroiled in controversy in the past year. In August, the Government Accountability Office declared that Wolf was unlawfully elevated to his position as part of a series of appointments that violated federal succession rules. The congressional watchdog said both Wolf and McAleenan were invalidly promoted to their roles following Nielsen’s resignation last spring.

DHS has dismissed the findings as “baseless” and politically motivated.

Rep. Bennie Thompson, D-Miss., who chairs the Homeland Security Committee, questioned the timing of Wolf’s resignation, noting lawmakers and other government officials have questioned for months whether he “has been serving illegally in his position.”

“He has chosen to resign during a time of national crisis and when domestic terrorists may be planning additional attacks on our government. Unlike others, he is apparently not leaving the Trump Administration on principle,” Thompson said in a statement Monday. 

“If it is true he is resigning because of recent federal court decisions, then it is an admission that his policy decisions are indeed invalid. Under this scenario, Ken Cuccinelli must also resign,” he said, a reference to Homeland Security’s acting deputy secretary. 

[GAO says Wolf, Cuccinelli appointments at DHS invalid]

Wolf’s appointment has been ruled unlawful by several federal judges since the GAO’s findings. Last month, a New York federal judge ruled that Wolf’s order to pause the Deferred Action for Childhood Arrivals program could not stand, and ordered applications to continue.

Most recently, a U.S. District Judge in California blocked a Trump administration rule that would have dramatically changed asylum policy. The judge in the case said Wolf, who was in charge when the rule was proposed and finalized, lacked authority to implement the policy.

Democratic lawmakers have also heavily criticized Wolf because of the excessive force and military tactics federal DHS officers used on protesters last year amid nationwide rallies against police brutality. Wolf defended the department’s actions, saying DHS acted within its authority to deploy hundreds of officers and agents to the nationwide protests.

Rep. Veronica Escobar, a Texas Democrat whose district includes the border town of El Paso, criticized Wolf’s hard-line immigration stance. 

“Chad Wolf helped create the immoral family separation policy, undermined our asylum system, oversaw and implemented inhumane policies like Remain in Mexico, violated the First Amendment, and tried to unlawfully rewrite the SCOTUS DACA decision,” she said in a tweet. “No one will miss him.”