WASHINGTON, D.C. — Congress’ Democratic leaders on Thursday demanded President Donald Trump’s removal from office — vowing a swift impeachment, if necessary — in an effort to stop him from unleashing more chaos in his final, rage-filled days.

Both House Speaker Nancy Pelosi and Senate Minority Leader Charles E. Schumer called on Trump’s Cabinet to oust him by invoking the 25th Amendment, which was designed to remove a president who is incapacitated or unwell. They warned that the House would quickly consider impeachment articles if that does not happen.

Schumer said he and Pelosi tried to call Vice President Mike Pence on Thursday morning to urge him to follow the 25th Amendment, but Pence would not take their call.

“While there are only 13 days left, any day could be a horror show for America,” Pelosi said, calling Trump “a very dangerous person who should not continue in office” and adding: “This is urgent, an emergency of the highest magnitude.”

Dozens of House Democrats, including some from conservative districts, echoed the call for a second impeachment and at least one Republican called for Trump’s removal by the Cabinet.

But forcibly ousting a president — even if a Cabinet were to invoke the 25th Amendment — is a laborious, time-intensive process. And even if Trump were impeached again, removing him requires a two-thirds vote of the Republican-controlled Senate, which acquitted him nearly a year ago, after his first House impeachment, and has shown no sign of openness to the idea now.

It was not at all clear Thursday if Trump could be prevented from serving out the remaining 13 days of his term, short of his resignation.

After a day in which pressure mounted to drive him from office before Jan. 20 — not just from Democrats but from some Republican governors and the conservative editorial board of The Wall Street Journal — Trump finally delivered what amounted to a concession speech to try to mollify the critics. But his video statement was probably too little, too late to quiet the clamor.

To expedite impeachment, House Democrats were considering starting the process on the House floor, without waiting for the House Judiciary Committee to act.

As longtime supporters rushed to distance themselves from a lame-duck president whose unhinged behavior has put the nation on edge, the political wreckage has left his party in distress and divided.

Transportation Secretary Elaine Chao, wife of Senate Majority Leader Mitch McConnell, R-Ky., Education Secretary Betsy DeVos and other White House officials resigned their posts, and Trump’s head of Homeland Security, his former attorney general and two former chiefs of staff condemned him.

Some allies who had been loath to criticize a president who demands absolute loyalty broke ranks, calling his behavior indefensible.

“The president needs to understand that his actions were the problem, not the solution,” said Sen. Lindsey Graham, R-S.C., who has been one of the most prominent apologists for Trump.

Graham said he is contemplating supporting the Cabinet’s resort to the 25th Amendment. “If something else happens, all options would be on the table,” he said, adding, “I am hopeful that the worst is behind us and that we can transfer power on Jan. 20.”

Former Trump chief of staff John F. Kelly has seen enough. He told CNN that if he were still in the Cabinet, he would be working with his colleagues to remove Trump immediately.

Whispers about the president being removed from office involuntarily ricocheted through Washington, as did grim assessments of Trump’s political future. But most Republicans were reluctant to talk publicly, continuing to hedge amid worries that Trump will prove resilient even from the fallout of his supporters’ riot Wednesday at the Capitol — as he has from so many other infamous episodes in his political career.

“A lot of people figure Inauguration Day cannot get here soon enough,” said a beleaguered House GOP leadership aide. “He certainly damaged himself.”

The bedlam in the Capitol also unsettled party leaders attending the winter meeting of the Republican National Committee in Florida. When RNC Chair Ronna McDaniel addressed the riot, she was so upset she cried, according to two sources at the meeting. But when Trump called into the meeting Thursday, he did not mention the violence. While some cheered him, others remained silent.

The quandary for Republicans was distilled on Wednesday during Congress’ session ratifying the presidential election results, when Trump allies challenged the outcome on his behalf. More than 100 House Republicans stuck with the president even after the Capitol had been overrun by rioters just after Trump addressed the crowd and urged them to fight for him.

Yet the earlier speculation among some Republicans that Trump could win back the White House for them in 2024 had gone silent. Of his legacy, veteran Republican strategist Mike DuHaime said, “If it is not destroyed, it is very damaged.”

Even Pence, Trump’s staunchest loyalist, distanced himself from Trump after the president called the rioters “special people” and said “we love” them. Pence condemned the mob in sharp terms as he presided over the Senate late Wednesday night.

“The vice president demonstrated yesterday that he was in charge, that he was demonstrating leadership,” said Jon Thompson, a former Pence adviser. “I don’t think we can say the same thing for President Trump.”

The relief when Trump finally leaves office will be bipartisan, but many Democrats seeking his early removal privately are resigned they’ll probably have to wait until Inauguration Day.

The House’s impeachment move is more symbolic — Democrats say they can’t let the account of the Capitol siege appear in history books without a response.

Rep. Ted Lieu, D-Calif., called it “important to show future generations that Congress didn’t just ignore what happened yesterday and that we put on record our efforts to try to remove a president that instigated an attempted coup.”

House Judiciary Committee Chairman Jerrold Nadler, D-N.Y., said the articles of impeachment lodging charges against Trump should be brought to the floor immediately, bypassing his panel. With the House adjourned, members were discussing whether to try to convince Democratic leaders to call members back to vote.

The risk of House Democrats moving quickly to impeach the president is that it could tarnish the action if hearings are not held and Trump is not given time to respond.

There is also discussion about the House voting to censure the president. But Schumer touted impeachment as an opportunity to prohibit Trump from ever again occupying the Oval Office, saying, “That should be invoked.”

One prominent Democrat who was notably silent on the issue was the man who will replace Trump on Jan. 20.

Joe Biden angrily denounced Trump’s actions around the Capitol siege during an event to introduce his nominee for attorney general, Merrick Garland. But he announced at the top of the news conference in Wilmington, Delaware, that he would not address the movement to expel Trump. He and Vice President-elect Kamala Harris ignored shouted questions as they left the room.

A statement from Biden’s transition team said he and Harris “will leave it to Vice President Pence, the Cabinet and the Congress to act as they see fit.”

The two Democrats instead focused Thursday on their promise to restore the rule of law by appointing leaders at the Justice Department who will not answer to them, but to the Constitution. Both critically contrasted the restraint that law enforcement showed against the predominantly white attackers who terrorized Congress with the force used in the summer against Black Lives Matter protesters.

“We witnessed two systems of justice,” Harris said. “We saw one that let extremists storm the U.S. Capitol and another that released tear gas on peaceful protesters last summer.”

Just before Biden and Harris took the stage, Chao announced her resignation as transportation secretary in a letter that said she was motivated by her distress over the Capitol mayhem that Trump inspired. McConnell, Chao’s husband, had broken with Trump just before the siege, in a forceful floor speech debunking Trump’s false claims that widespread election fraud and other improprieties deprived the president of a second term.

But his and Trump’s critics declared it too little, too late. They pilloried Chao for leaving her post instead of staying put and initiating an effort with her colleagues to invoke the 25th Amendment.

The Cabinet, though, probably has little power to jettison Trump from the Oval Office with so few days left in his term. The 25th Amendment is complicated, and its procedures can take a month to work through. In the more than half-century it has been in the Constitution, it has never been used to involuntarily sideline a sitting president.

House Majority Whip James E. Clyburn, D-S.C., acknowledged as much. “Time and circumstances may mitigate against invoking the 25th Amendment, which I support,” he tweeted, “but there is time for impeachment which seems appropriate.”