IT HAS been a handful of days since a violent mob stormed the Capitol on President Trump’s encouragement, and the consequences of this desecration are only beginning to emerge. The nation’s allies are distraught. Its enemies are cheering. Americans are shaken. And by all accounts, the president’s instability remains a threat to the security of the government and, indeed, to all citizens.

For the next two weeks, Washington has one overriding task: making the transition to the inauguration of President-elect Joe Biden with as little further damage as possible. Mr. Trump must be held accountable for his inexcusable incitement and prevented from further reckless ventures at home or abroad. The powers of the presidency are wide; unchecked, Mr. Trump could prompt more unrest, a war, a domestic crackdown or who knows what else.

Vice President Pence bears prime responsibility to protect the country from Mr. Trump. He reportedly opposes invoking the 25th Amendment to sideline the president, on the grounds that it would only stoke more chaos. On Thursday, Mr. Trump delivered a prepared statement in which he promised “an orderly transition.” But the benefits of declaring the president unfit would outweigh the drawbacks should he once again try to abuse his powers or platform. Mr. Pence and the Cabinet must prepare to change their minds and act immediately if the president’s post-election meltdown — reflecting an undeniable mental incapacity — results in more reckless behavior.

Democrats may be moving toward impeaching Mr. Trump a second time, but at best, that will take considerable time and faces an uncertain outcome in a Senate still under Republican control. The president is a threat now. He should face a quick and bipartisan condemnation aimed at showing him that much of his party no longer stands behind him. Lawmakers can do that by censuring Mr. Trump for inciting Wednesday’s riot. The language should be clear: Mr. Trump is responsible for the mob he instructed to gather on Jan. 6 and told to march on the Capitol and show “strength.”

Whatever else Congress may do, such a resolution would put into formal legislative action the sense, expressed by many Republicans and conservative commentators, that Wednesday was the defining moment of Mr. Trump’s presidency. It would also force those Republican lawmakers who still seek some spineless middle path between crossing the president and defending the nation’s system of government to finally choose whether they stand with Mr. Trump or with the country. Many Republicans — a distressingly substantial number — would still raise their hands as die-hard Trump supporters. But many would not, and this action would help force the intraparty reckoning Republicans know they must now have.

Censure would in no way represent a sufficient punishment for Mr. Trump or a proportional reaction to Wednesday’s crimes. Congress, the Republican Party, the next administration, social media companies and many, many others will have to grapple further with Jan. 6 in the coming days. But it is a place to start. Meanwhile, Mr. Pence and the Cabinet must prepare themselves to act if the president retreats from his latest promise to go quietly.

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