Acting Homeland Security Secretary Chad Wolf will step down from his position, Fox News first reported and Axios has confirmed.

Why it matters: Word of Wolf's departure comes a week before the inauguration and the massive security concerns following the Capitol siege.

• Wolf's announcement comes after last week's departure of Transportation Secretary Elaine Chao and Education Secretary Betsy DeVos, among numerous administration departures following the Capitol riot.
• Wolf was one of President Trump's Cabinet members who called on him to condemn the pro-Trump mob that stormed the U.S. Capitol.
• The White House withdrew Wolf's nomination as permanent Homeland Security chief last week.

What he's saying: "Effective at 11:59 p.m. today, I am stepping down as your Acting Secretary. I am saddened to take this step, as it was my intention to serve the Department until the end of this Administration," he said in a letter to colleagues.

• "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, apparently referring to several court rulings that said he was illegally appointed to his post.
• "I leave knowing that the Department has positioned itself for an orderly and smooth transition to President-elect Biden’s DHS team," Wolf said. "Welcome them, educate them, and learn from them. They are your leaders for the next four years — a time which undoubtedly will be full of challenges and opportunities to show the American public the value of DHS and why it is worth the investment."

The big picture: Wolf, who has been consistently supportive of Trump, led the department through a tumultuous period as the president focused on the agency's role in immigration enforcement and policymaking.

• The agency also faced widespread criticism from Democrats over federal crackdowns in Portland and other cities during Black Lives Matter protests.

What's next: Wolf said that FEMA administrator Pete Gaynor would take over his position as acting DHS secretary.

Editor's note: This story has been updated with additional information throughout.