Democratic leaders have called for Donald Trump to be forced from office before his term ends on 20 January for his role in inciting what his successor, Joe Biden, described as “one of the darkest days” in US history.As a new 7ft fence was belatedly erected around the US Capitol on Thursday, an inquiry was launched into why the seat of US democracy was left so poorly defended against a predictable assault.But the principal political focus was on the dangers of allowing a president widely seen as being the ultimate instigator of Wednesday’s mob attack to retain power in the remaining two weeks before Biden’s inauguration.The president-elect said Wednesday’s insurrection marked “one of the darkest days in the history of our nation”, saying the attack was carried out by “domestic terrorists”. Biden accused his predecessor of unleashing an “all-out attack” on the country’s democratic institutionsChuck Schumer, who is the incoming Senate majority leader following the Democratic sweep of Georgia, and the House speaker, Nancy Pelosi, called for Trump to be removed through the 25th amendment to the constitution, which allows for a president to be replaced by their vice-president, if they become incapable of doing their job.Failing that, they argued he should be impeached for a second time.Pelosi described Trump as “a very dangerous person who should not continue in office”.“This is urgent. This is an emergency of the highest magnitude,” Pelosi said.Several Democratic members of Congress drafted new articles of impeachment for inciting Wednesday’s violence and deliberating subverting US democracy.“What happened at the US Capitol yesterday was an insurrection against the United States, incited by President Trump. This president must not hold office one day longer. The quickest and most effective way – it can be done today – to remove this president from office would be for the Vice President to immediately invoke the 25th amendment,” Schumer said in a tweet.“If the Vice President and the Cabinet refuse to stand up, Congress must reconvene to impeach President Trump.”Charges for Trump’s second impeachment were drawn up by several Democratic congress members – Ilhan Omar, Ted Lieu, Jamie Raskin and David Cicilline – accusing him of “wilfully inciting violence against the government of the United States” and warning he remained “a threat to national security, democracy and the constitution, if allowed to remain in office”.Use of the 25th amendment, on the grounds unfitness for office is a form of incapacity, would rely on the cooperation of Republicans including the vice-president, Mike Pence, who would take over the administration in its final two weeks. That seemed unlikely on Thursday.Adam Kinzinger of Illinois, a frequent Republican critic of Trump, joined the calls for the 25th amendment to be invoked, saying in a video message: “The president must now relinquish control of the executive branch voluntarily or involuntarily.”But the GOP leadership did not appear sufficiently shocked to jettison their leader, who was reportedly warmly received on a conference call with the Republican National Committee on Thursday morning.There was a handful of resignations by second-tier officials, including the transport secretary, Elaine Chao (married to the current Senate majority leader, Mitch McConnell); the deputy national security adviser, Matthew Pottinger; the Northern Ireland envoy (and former White House chief of staff), Mick Mulvaney; and the first lady’s spokeswoman, Stephanie Grisham. But there was no sign yet of a sweeping exodus or mutiny that would be required to force the president from office.Trump loyalists in Congress and on Fox News quickly began circulating groundless conspiracy theories that disguised members of the leftist antifa movement had provoked the insurrection.The president himself made no public statements on Thursday, and after a call with the Republican National Committee spent part of the day awarding the presidential medal of freedom to two golf players and one Olympic athlete, one of them posthumously.Facebook imposed an indefinite ban on Trump, whose campaign has long used the platform to spread disinformation and conspiracy theories. The decision may also have been influenced by the Democratic success in taking control of the Senate.Former administration officials were scathing about the president’s role, most notably the recently departed attorney general, William Barr, who said Trump was guilty of “betrayal of his office and supporters” by “orchestrating a mob to pressure Congress.”.The former defence secretary James Mattis said Trump “fomented” the attack, intended “to subjugate American democracy by mob rule”.But current Republican leaders were much more guarded. McConnell said the blame for the attack lay with the “unhinged criminals” who carried it out “and with those who incited them” but did not name the president.Lindsey Graham, one of Trump’s top congressional allies, called on the president to accept his own role in the violence, saying that Trump “needs to understand that his actions were the problem, not the solution”.But asked about calls for Trump to be removed from office, the South Carolina senator said: “I do not believe that is appropriate at this point. I’m looking for a peaceful transfer of power.”A YouGov poll of Republicans found 45% of them supported the storming of the Capitol, 2% more than those who opposed it.At least some of Trump’s leading supporters abroad sought to distance themselves, including Boris Johnson, who said it was “completely wrong” for Trump to “encourage people to storm the Capitol” and cast doubt on the election result.In Washington, law enforcement agencies tried to respond to widespread outrage over the apparent impunity of the insurrectionists (only 14 of whom had been arrested by Thursday afternoon) and the lack of adequate defences for a vital organ of government.McConnell said it was a “massive failure” and called for a full investigation. The congressional sergeant at arms, responsible for overall security in the building, resigned on Thursday but Pelosi called for the chief of the Capitol police, Steven Sund, to step down as well.Sund issued a statement saying the storming of the legislature was “unlike any I have ever experienced in my 30 years in law enforcement here” and argued that his officers had been spread thin by having to respond to two pipe bombs found near the Capitol at the same time as the assault.Pelosi also said she had not received a satisfactory reply from the defence secretary, Christopher Miller, on why the national guard was so slow to respond, arriving in significant numbers only after the Capitol was occupied.The army secretary, Ryan McCarthy, told reporters that he had expected Wednesday’s events to be like other recent protests, adding that Pentagon officials had not imagined a breach of the Capitol in their “wildest imagination”.The head of the Washington metropolitan police department also claimed: “There was no intelligence that suggests that there would be a breach of the US Capitol.” Critics responded that those responsible had telegraphed their intentions in advance.“It was all in the open on public social media sites, not to mention in the President’s speech,” John Sipher, a former senior CIA officer, commented on Twitter. 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