Democrats have been plunged into a bitter row ahead of their national convention next week after Alexandria Ocasio-Cortez, the firebrand left-wing congresswoman, was given just 60 seconds to speak.
Ms Ocasio-Cortez, 30, a lightning rod for proponents of policies like the Green New Deal and universal healthcare, will get less time than John Kasich, the Republican former governor of Ohio, and Michael Bloomberg, the billionaire media mogul. Her remarks will also be pre-recorded.
She responded by posting on Twitter lines from "God's Minute," a poem by the civil rights leader Dr Benjamin E. May.
The New York congresswoman wrote: “I only have a minute. Sixty seconds in it. Forced upon me, I did not choose it, But I know that I must use it.
"Give account if I abuse it. Suffer, if I lose it. Only a tiny little minute, But eternity is in it."
Her extensive following on social media lambasted the decision as the party's "old guard" delivering a "slap to the progressive wing".
The row exposed the divide that remains between moderate supporters of Joe Biden, and those of Bernie Sanders, his vanquished opponent for the presidential nomination. Ms Ocasio-Cortez fervently backed Mr Sanders.
David Sirota, a former speechwriter for Mr Sanders, said: "Hey, at least AOC is getting a 60 second ad during the intermission at the Kasich Bloomberg Show."
The event itself, which formally begins Monday, was supposed to take place in Milwaukee, in the key battleground state of Wisconsin.
But, due to the coronavirus pandemic, it will be the first all-virtual party convention. There will be no single gathering place, no cheering audience, no balloons and ticker tape, and no backroom deals over the party's policy platform.
Instead, for two hours each evening, speakers will deliver a series of online video addresses, half of them prerecorded like Ms Ocasio-Cortez's.
Barack Obama, Michelle Obama, Bill Clinton and Hillary Clinton will be among the speakers.
Kamala Harris, Mr Biden's running mate and the first woman of colour on a major US presidential ticket, will speak on Wednesday.
The following night Mr Biden will formally accept the presidential nomination in a mostly empty ballroom in Delaware.
Mr Trump accused Democrats of "ignoring Wisconsin" and said he would physically campaign there on Monday as their virtual convention opens.
He called Ms Harris "sort of a mad woman" and "angry".
The president also took aim at Ms Ocasio-Cortez. He said: "AOC was a poor student. This is not even a smart person, other than she's got a good line of stuff. I mean, she goes out and she yaps. These guys, they're all afraid of her."
Ms Ocasio-Cortez responded: “Let’s make a deal, Mr President. You release your college transcript, I’ll release mine, and we’ll see who was the better student. Loser has to fund the Post Office."
Her comments came as it emerged the US Postal Service had written to election officials in 46 states warning that millions of ballots cast by mail may not arrive in time to be counted.
There is expected to be an explosion in mail-in voting due to the pandemic, but the post office has faced cuts recently.
Mr Kasich stood for the Republican nomination in 2016, debating Mr Trump numerous times. In a large field he finished third in the popular vote with over four million.
Asked why he was speaking at the Democrat convention, Mr Kasich said: "Conscience. There's almost hatred going on. This has to stop. I've had enough of this. I've known Joe [Biden] for 30 years. I know the kind of guy he is."