The last chapter in the presidency of Donald Trump has come down to this: Under what circumstances will he leave office and how much will that departure further sully an already besmirched legacy.

The end is coming in ways Trump could not have imagined before Wednesday’s riot at the Capitol by his supporters. He is hearing calls for his resignation from conservative voices, among them Rupert Murdoch’s Wall Street Journal editorial page.

Members of his Cabinet and White House staff are deserting him, though perhaps too late to escape the fallout from having stood by him for so long. Twitter has banned him permanently due to the risk of further incitement of violence, denying him the favored platform for his incendiary messaging and attacks on rivals.

More ominously, he faces the prospect of being impeached for a second time by House Democrats, led by Speaker Nancy Pelosi (D-Calif.). Were that to happen, Trump would stand alone among the nation’s presidents for such ignobility.

Absent a resignation or a move by Vice President Pence to lead the invoking of the 25th Amendment, for which Pence shows no stomach, impeachment proceedings could be on a fast-track. In just a few days, the idea of impeachment has gone from preliminary conversations to the prospect of possible floor action early next week, if Trump has not resigned.

Trump’s role in whipping up the mob that invaded and then desecrated the U.S. Capitol, the most visible symbol of American democracy, has left the president with few defenders. There are the last bitter-enders of the nativist army that has provided aid and comfort to him for five years. There are the members of the Republican National Committee, who met and cheered the president in Florida on Friday.

There are still some allies in Congress, though fewer than ever. Even before the Capitol was overrun, Trump had been abandoned by Senate Majority Leader Mitch McConnell (R-Ky.), who voted against objections to the electoral count and made his opposition clear in a stinging floor statement.

The president’s relationship with Pence has been ruptured because the vice president did the constitutionally limited — and correct — thing in presiding without interference over the counting of the electoral college votes that made official President-elect Joe Biden’s victory. Trump apparently cannot understand why the vice president would stand with the Constitution. The absence of a commitment to the Constitution has been a persistent defect of Trump’s presidency.

The Washington Post and others have drawn vivid portraits all week of a bunkered and embittered president, surrounded by only a few advisers. Under pressure, he sent out a video Thursday evening asking that “tempers be cooled” and acknowledging that there would be a new administration on Jan. 20. He said that his focus now would be on assuring a “smooth, orderly and seamless” transition. He did not mention Biden or offer congratulations.

On Friday, before the permanent suspension from Twitter, he tweeted that the nearly 75 million people who voted for him will have “a giant voice” in the future and are not to be “disrespected” or treated unfairly. Later he tweeted that he would not attend Biden’s inauguration, the first president in more than a century to skip a ceremony that would have signaled his admission that the election was fairly decided.

Two issues lie behind the moves to force Trump from office. One is the issue of clear and present danger, or more simply, what further damage could be done by a temperamentally fragile president in the final days.

Pelosi took the extraordinary step of publicly revealing that she had talked with Gen. Mark A. Milley, chairman of the Joint Chiefs of Staff, to discuss “available precautions for preventing an unstable president from initiating military hostilities or accessing the launch codes and ordering a nuclear strike.”

Pelosi’s expressed fears were alarmingly direct in language, but this was not the first time the issue of what Trump might do with his commander in chief powers in the final days had been raised by those who have served in government. Earlier, the 10 living former defense secretaries had warned Pentagon leaders not to involve the military in any election disputes and pointed to severe consequences for those leaders if they allowed that to happen.

To some people, the easiest way out to alleviate worries about what Trump might do in his remaining days would be a quick presidential resignation and the elevation of Pence to the presidency until Biden is sworn in. Those who favor resignation see impeachment as prolonged and divisive and view the use of the 25th Amendment, in which Pence and a majority of the Cabinet would declare Trump unable to discharge his duties, as a far messier conclusion to his presidency.

The other issue driving talk of impeachment is accountability for stoking the violence against the Capitol. The draft impeachment language prepared by House Democrats makes that role the basis for the charge against the president.

Impeachment and conviction, were the Senate to take such action, would do something else: It would deny Trump the opportunity to ever serve as president for a second time. Trump closed his Thursday night video by telling his supporters that “our incredible journey is only just beginning.” He has been dangling the possibility of another campaign for president in 2024, perhaps to be launched as he left office.

Until Wednesday’s attack on the Capitol, he was seen as capable of continuing his role as the most prominent and powerful leader of the Republican Party and of freezing the field of 2024 GOP presidential aspirants for a possible run of his own or to play kingmaker.

Twitter on Jan. 8 banned President Trump from its site, a punishment for his role in inciting violence at the U.S. Capitol. (The Washington Post)

His diminished status could lessen the likelihood that the party would turn to him again as its presidential nominee, though he has been counted out before and continues to enjoy support at the grass-roots level and among some party officials. Impeachment would take that question off the table permanently.

Biden was asked about impeachment on Friday and tried to deflect. He said any such decision should be left to lawmakers in Congress and that he would continue to focus on preparations to become president. It was neither a rejection nor an endorsement, and he reiterated that he has long seen Trump as unfit for office. He said he believed the fastest way to have Trump removed is to let the Constitution work and await the end of Trump’s term at noon Jan. 20.

A possible impeachment trial could tie up the Senate just as Biden is beginning his presidency. That would delay such Biden priorities as confirmation of Cabinet members and action on a trillion-dollar coronavirus relief package that he said would be his first legislative priority. These are hardly the ideal circumstances for the incoming president but not surprising given the history of Trump in office.

House Minority Leader Kevin McCarthy (R-Calif.) said Friday that impeachment would only further divide a divided nation at a time when, he argued, healing is needed. Democrats see those as hollow words, coming from someone who helped give support to the president’s falsehoods about a stolen election and who voted in favor of objections to the counts in Arizona and Pennsylvania even after Trump’s supporters ransacked the Capitol. McCarthy is not the only Republican now trying shamelessly to scramble to higher ground.

There will be consequences of acting to remove the president and consequences of not acting. Time is short and the president’s responsibility for what took place on Wednesday undeniable. However and whenever he leaves the White House, he will be forever marked by his final days in office.