Pressure is mounting on US President Joe Biden after a faltering debate performance against Donald Trump. Once-friendly media heavyweights have joined the chorus of derision.Is it time for Joe to go?

Amid a howling chorus of derision over Joe Biden's substandard debate performance against Donald Trump last week, one voice seemed to resonate more powerfully than others.

- Robert Tait

At 6.15pm last Friday - roughly 19 hours after the two presidential candidates left the stage in Atlanta the previous evening - the verdict of the New York Times's editorial board dropped online to the newspaper's subscribers.

The judgment was devastating. The US president, the board forcefully argued, had presented such an alarming spectacle of aged frailty that the best thing he could now do for the country he had served for more than half a century was to withdraw from the race and allow his Democratic party to choose another candidate.

The newspaper long venerated as "the old Grey Lady" of American journalism pointed out that Biden had presented himself as the figure best positioned to defeat the threat to democracy represented by Trump - and acknowledged that he had successfully done so in 2020.

"But the greatest public service Mr Biden can now perform is to announce that he will not continue to run for reelection," it intoned.

"As it stands, the president is engaged in a reckless gamble. There are Democratic leaders better equipped to present clear, compelling and energetic alternatives to a second Trump presidency... It's too big a bet to simply hope Americans will overlook or discount Mr Biden's age and infirmity that they see with their own eyes."

The judgment evoked memories of February 1968, when Walter Cronkite, the magisterial CBS anchor, used his television platform to openly question the US military commitment in Vietnam after the Vietcong launched an offensive that led to guerrillas storming the US embassy compound in Saigon. Watching, President Lyndon Johnson - another Democratic president, to whom Biden is sometimes compared reportedly said: "If I've lost Cronkite, I've lost Middle America."

Just over a month later, Johnson withdrew from that year's presidential election.