Michelle Obama has launched a stinging attack on US President Donald Trump as Democrats prepare to crown Joe Biden as their White House challenger.
"Donald Trump is the wrong president for our country," said the former US first lady in an emotional recorded message to the Democratic convention.
Disaffected members of Trump's Republican party also piled in to show their opposition to him at the Democratic party conference.
Trump, who trails Biden in opinion polls, hit back.
Because of the coronavirus outbreak, Democrats scrapped plans for a crowded party extravaganza with balloon drops and all the other political razzmatazz in Milwaukee, Wisconsin.
But it is unclear whether the largely virtual schedule of pre-recorded speeches with no live audience can generate the same level of enthusiasm as pre-pandemic gatherings of the party faithful.
Republicans will face the same challenge as they make their case for four more years in the White House at a drastically scaled-down convention next week.
What did Michelle Obama say?
Obama, who recorded her keynote address before Biden announced his running mate, Senator Kamala Harris, six days ago, launched a blistering attack on Trump.
"You simply cannot fake your way through this job," she said in remarks that closed the first night of the convention on Monday.
The headline speaker added: "Our economy is in shambles because of a virus that this president downplayed for too long."
"Stating the simple fact that black life matters is still met with derision from the nation's highest office," Obama continued.
"Because whenever we look to this White House for some leadership, or consolation, or any semblance of steadiness, what we get instead is chaos, division and a total and utter lack of empathy."
She said the last four years has been difficult to explain to America's children.
"They see our leaders labelling fellow citizens enemies of the state, while emboldening torch-bearing white supremacists.
"They watch in horror as children are torn from their families and thrown into cages, and pepper spray and rubber bullets are used on peaceful protests for a photo op."
Obama continued: "Donald Trump is the wrong president for our country. He has had more than enough time to prove that he can do the job, but he is clearly in over his head.
"He simply cannot be who we need him to be for us. It is what it is."
She described Biden as a "profoundly decent man", touting the Democratic White House candidate's experience as vice-president under her husband, President Barack Obama.
"We have got to vote for Joe Biden like our lives depend on it," she said, wearing a necklace that said "Vote".
What else happened on Monday?
The opening night of the convention, a two-hour programme hosted by former Desperate Housewives actress Eva Longoria Baston, was titled by party organisers: "We the People".
Kasich recorded a message calling on Americans to deny the president a second term in office.
Kasich endorsed Biden, saying: "We can all see what's going on in our country today and all the questions that are facing us, and no one person or party has all the answers.
"But what we do know is that we can do better than what we've been seeing today, for sure."
Sanders also recorded a message, he said: "My friends, I say to you, and to everyone who supported other candidates in this primary and to those who may have voted for Donald Trump in the last election: The future of our democracy is at stake. The future of our economy is at stake. The future of our planet is at stake."
He added: "Nero fiddled while Rome burned - Trump golfs."
Along with Kasich, three other high-profile Republicans recorded messages for the convention's opening night: California businesswoman Meg Whitman, former New Jersey Governor Christine Whitman and former New York congresswoman Susan Molinari.
While their inclusion left the Biden team claiming a broad coalition, some Democrats grumbled that the Republicans used up precious time that could have benefited progressive speakers or lesser-known rising stars.
But Cedric Richmond, a Louisiana congressman and Biden campaign co-chairman, rejected that idea, saying, "remember tonight's theme is 'We the People,' not 'We the Democrats'".
The opening night also featured pre-recorded messages from everyday Americans, including repentant Trump voters and a woman who blamed her father's death of Covid-19 on the president.
How did President Trump hit back?
Speaking to the BBC on Air Force One as he flew back from a trip to the presidential swing-voting states of Minnesota and Wisconsin, Trump lashed out at Kasich.
"He was a loser as a Republican, and he'll be a loser as a Democrat," the president said on Monday. "The guy was a major loser as a Republican."
During a campaign speech earlier in the day in Mankato, Minnesota, Trump warned that if Biden won in November, news outlets would lose their audiences.
"Nobody's going to want to cover sleepy Joe," Trump said. "We will end up with one very boring socialist country that will go to hell."
Trump on Monday also confirmed he would accept the Republican nomination for a second term during a live speech at the White House next week.
His plans have been criticised by Democrats and even some fellow Republicans.
How will the rest of the Democratic convention play out?
The four-night jamboree will culminate in Biden's speech on Thursday in a mostly empty ballroom in his home state of Delaware.
On Wednesday, his vice-presidential pick, Harris, the daughter of immigrant parents from India and Jamaica, will accept her nomination as the first woman of colour to be a running mate on a major party presidential ticket.
Also speaking on Wednesday are former-President Barack Obama, 2016 Democratic nominee Hillary Clinton, and one of Biden's former rivals, Senator Elizabeth Warren.
Tuesday will hear speeches from former- President Bill Clinton and congresswoman Alexandria Ocasio-Cortez.