Impeachment article has 200 cosponsors: US rep.

Education Secretary Betsy DeVos has resigned, according to a letter obtained by ABC News Thursday night.

She is the second Trump Cabinet member to step down in the wake of Wednesday's storming of the Capitol, following Transportation Secretary Elaine Chao's resignation earlier Thursday.

In her resignation letter, addressed to Trump, DeVos cited the president's role in Wednesday's "unconscionable" attack on the Capitol.  

"We should be highlighting and celebrating your Administration's many accomplishments on behalf of the American people," she wrote. "Instead, we are left to clean up the mess caused by violent protesters overrunning the U.S. Capitol in an attempt to undermine the people's business."

"There is no mistaking the impact your rhetoric had on the situation, and it is the inflection point for me," she added.

The resignation is effective Friday, according to the letter.

She joins a growing list of other Trump officials to resign following the Capitol breach.

-ABC News' Sophie Tatum contributed to this report

Following the resignation of the House sergeant-at-arms and the Capitol police chief, Senate Majority Leader Mitch McConnell announced Thursday night that he’s received the resignation of the Senate sergeant-at-arms.

This comes following Senate Minority Leader Chuck Schumer’s statement earlier Thursday that he would fire the Senate sergeant-at-arms when Democrats claim the majority in the chamber if he did not resign.

“Today I requested and received the resignation of Michael Stenger, the Senate Sergeant at Arms and Doorkeeper, effective immediately," McConnell said in a statement Thursday.

“Deputy Sergeant at Arms Jennifer Hemingway will now serve the Senate as Acting Sergeant at Arms, pursuant to statute," McConnell continued. "I thank Jennifer in advance for her service as we begin to examine the serious failures that transpired yesterday and continue and strengthen our preparations for a safe and successful inauguration on January 20th.”

-ABC News' Allison Pecorin

For the first time since losing the election to President-elect Joe Biden, President Donald Trump acknowledged he lost.

A new administration will be inaugurated on Jan. 20, he said. 

“My focus now turns to ensuring a smooth, orderly and seamless transition of power,” Trump said in a video Thursday night.

Trump also spoke directly to his supporters, saying serving as president has been the honor of his lifetime.

“To all of my wonderful supporters, I know you’re disappointed, but I also want you to know that our incredible journey has only just begun.”

The president did not congratulate Biden or recognize him as the president-elect in the video.

His speech comes a day after a pro-Trump mob breached the Capitol, in an incident that left at least four people dead and forced Congress to evacuate and seek shelter in the middle of certifying the electoral votes.

Thursday night, the president spoke of the need for peace and calm, a day after speaking to those same pro-Trump protesters, saying he would never concede.

“This moment calls for healing and reconciliation,” Trump said Thursday night.

A spokeswoman for the United States Capitol Police has confirmed to ABC News that Capitol Police Chief Steven Sund is resigning, effective Jan. 16.

The resignation comes after rioters seized the Capitol building on Wednesday and following House Speaker Nancy Pelosi calling for him to step down due to the botched response.

Sund does not mention the Capitol riot in his three-sentence resignation letter. "It has been a pleasure and true honor to serve the United States Capitol Police Board and the Congressional community alongside and the women and men of the United States Capitol Police," he wrote.

The Capitol Police Union had released a statement saying they were "frustrated and demoralized by the lack of leadership" and called for the chief and his deputy to resign. 

"We have several protesters dead, multiple officers injured and the symbol of our Democracy, the U.S. Capitol, desecrated. This never should have happened," Capitol Police Union Chairman Gus Papathanasiou said in a statement. 

"This lack of planning led to the greatest breach of the U.S. Capitol since the War of 1812," he added. This is a failure of leadership at the very top."

-ABC News' Mariam Khan, Benjamin Siegel and Luke Barr