Hillary Clinton has endorsed Joe Biden for president as the candidate prepares to face Donald Trump in the general election.

"Think if we had a real president, not just one who plays one on TV," she said during a virtual town hall on the impact of the coronavirus pandemic on women. "So many Americans wish they had that kind of leadership now ... This is a moment where we need a leader, a president, like Joe Biden."

The former US Secretary of State and 2016 candidate — introduced by the former vice president as "a woman who should be in the White House" — urged voters to "support the kind of person we want back in the White House" to "end the kind of disregard of American values, institutions, the rule of law, and so much that's at stake because of the current occupant."

Secretary Clinton said the current public health crisis has "stripped bare for everyone to see the inequalities" and institutional failures in the US.

"We need to be prepared to fix what is wrong in America to truly live up to the best versions of ourselves," she said.

She called the White House response "incoherent" led by the president's "impossibly insensitive approach" to the emergency.

"This is a moment of reckoning," she said. "That's what's really going to be on the ballot ... What kind of America are people going to be voting for?"

Secretary Clinton, who became the first woman to lead a major political party in a bid for the White House before her loss to Mr Trump, announced her support for Mr Biden as Democrats begin to coalesce around the candidate following the suspension of Bernie Sanders's campaign.

Democratic primaries: Who won where? Show all 27 1 /27 Democratic primaries: Who won where? Democratic primaries: Who won where? Arizona: Biden wins Joe Biden: 39 delegates Bernie Sanders: 28 delegates Getty Democratic primaries: Who won where? Alabama: Biden wins Joe Biden: 41 delegates Bernie Sanders: 7 delegates Michael Bloomberg: 1 delegate Reuters Democratic primaries: Who won where? Arkansas: Biden wins Joe Biden: 17 delegates Bernie Sanders: 9 delegates Michael Bloomberg: 5 delegates AFP/Getty Democratic primaries: Who won where? California: Sanders wins Bernie Sanders: 179 delegates Joe Biden: 127 delegates Michael Bloomberg: 15 delegates Elizabeth Warren: 5 delegates AP Democratic primaries: Who won where? Colorado: Sanders wins Bernie Sanders: 20 delegates Joe Biden: 9 delegates Michael Bloomberg: 9 delegates Elizabeth Warren: 1 delegate AFP/Getty Democratic primaries: Who won where? Florida: Biden wins Joe Biden: 152 delegates Bernie Sanders: 53 delegates Getty Democratic primaries: Who won where? Idaho: Biden wins Joe Biden: 11 delegates Bernie Sanders: 9 delegates EPA Democratic primaries: Who won where? Illinois: Biden wins Joe Biden: 95 delegates Bernie Sanders: 59 delegates AFP Democratic primaries: Who won where? Iowa: Buttigieg wins Pete Buttigieg: 14 delegates Bernie Sanders: 12 delegates Elizabeth Warren: 8 delegates Joe Biden: 6 delegates Amy Klobuchar: 1 delegates Reuters Democratic primaries: Who won where? Maine: Biden wins Joe Biden: 11 delegates Bernie Sanders: 9 delegates Elizabeth Warren: 4 delegates AFP/Getty Democratic primaries: Who won where? Massachussetts: Biden wins Joe Biden: 37 delegates Bernie Sanders: 29 delegates Elizabeth Warren: 25 delegates AP Democratic primaries: Who won where? Michigan: Biden wins Joe Biden: 72 delegates Bernie Sanders: 52 delegates Getty Democratic primaries: Who won where? Minnesota: Biden wins Joe Biden: 38 delegates Bernie Sanders: 27 delegates Elizabeth Warren: 10 delegates Reuters Democratic primaries: Who won where? Mississippi: Biden wins Joe Biden: 34 delegates Bernie Sanders: 2 delegates AFP via Getty Images Democratic primaries: Who won where? Missouri: Biden wins Joe Biden: 44 delegates Bernie Sanders: 24 delegates AP Democratic primaries: Who won where? Nevada: Sanders wins Bernie Sanders: 24 delegates Joe Biden: 9 delegates Reuters Democratic primaries: Who won where? New Hampshire: Sanders/Buttigieg tie Bernie Sanders: 9 delegates Pete Buttigieg: 9 delegates Amy Klobuchar: 6 delegates EPA Democratic primaries: Who won where? North Carolina: Biden wins Joe Biden: 66 delegates Bernie Sanders: 36 delegates Elizabeth Warren: 2 delegates Michael Bloomberg: 2 delegates AFP/Getty Democratic primaries: Who won where? North Dakota: Sanders wins Bernie Sanders: 8 delegates Joe Biden: 6 delegates Getty Democratic primaries: Who won where? Oklahoma: Biden wins Joe Biden: 21 delegates Bernie Sanders: 13 delegates Michael Bloomberg: 2 delegates Elizabeth Warren: 1 delegate Reuters Democratic primaries: Who won where? Florida: Biden wins Joe Biden: 152 delegates Bernie Sanders: 53 delegates Getty Democratic primaries: Who won where? Tennessee: Biden wins Joe Biden: 33 delegates Bernie Sanders: 18 delegates Michael Bloomberg: 10 delegates Elizabeth Warren: 1 delegate Reuters Democratic primaries: Who won where? Texas: Biden wins Joe Biden: 111 delegates Bernie Sanders: 102 delegates Michael Bloomberg: 10 delegates Elizabeth Warren: 5 delegates Reuters Democratic primaries: Who won where? Utah: Sanders wins Bernie Sanders: 12 delegates Joe Biden: 2 delegate Michael Bloomberg: 2 delegates AFP/Getty Democratic primaries: Who won where? Vermont: Sanders wins Bernie Sanders: 11 delegates Joe Biden: 5 delegates AP Democratic primaries: Who won where? Virginia: Biden wins Joe Biden: 66 delegates Bernie Sanders: 31 delegates Elizabeth Warren: 2 delegates AFP/Getty Democratic primaries: Who won where? Washington: Biden wins Joe Biden: 46 delegates Bernie Sanders: 43 delegates AP

He has recently secured endorsements not only from his chief rival but also from former president Barack Obama, House Speaker Nancy Pelosi and Elizabeth Warren, among other Democratic contenders in the 2020 race.

Her endorsement wasn't a surprise, but she joins the fray with a significant fundraising army and legions of supporters following his 2016 loss.

But her support will likely give Republicans more ammunition ahead of the 2020 contest, as Mr Trump's allies are eager to revisit attacks against the previous administration and the Clintons, as his campaign did in 2016.

In a statement, Trump campaign manager Brad Parscale said: "There is no greater concentration of Democrat establishment than Joe Biden and Hillary Clinton together ... Both of them carry the baggage of decades in the Washington swamp and both of them schemed to keep the Democrat nomination from Bernie Sanders."

Secretary Clinton largely sat out of the primary except to attack Senator Sanders — whom the Clinton campaign argued had hurt her election chances against Mr Trump in 2016, despite his endorsement of her after he left the race — as he emerged as the field's frontrunner in 2020.

Her endorsement this week during Mr Biden's women-focussed town hall also follows increased scrutiny over allegations against the candidate for allegedly sexually assaulting a staffer in the 1990s.

Their conversation on Tuesday criticised the president's response to the coronavirus outbreak as the number of Covid-19 cases in the US climbed above 1 million.

Following reports that the president had dismissed early reports from intelligence officials in his administration that urged the administrations to begin preparing for the outbreak, Secretary Clinton said: "One thing I would've done ... is I would've read my daily intelligence briefings. But apparently this president doesn't do what we used to do."

Mr Biden said: "Did he just not read ... or did he read and not care? I would give him the more generous view that he just didn't read it ... I can't fathom it."