Biden tells NAACP: ‘I know what a Black job is: it’s the vice-president’ of the US

Wielding a potentially potent attack line in his re-election campaign against Donald Trump, Joe Biden told the NAACP: “I know what a Black job is: it’s the vice-president of the United States.”

Related: Adam Schiff reportedly tells donors ‘I think we lose’ if Biden is nominee

Biden was speaking to the National Association for the Advancement of Colored People in Las Vegas, Nevada, as the group staged its 115th national convention.

Black voters form a key part of Biden’s base. His “Black jobs” line referred to controversial remarks by Trump in the first presidential debate, in Atlanta last month.

Then, Trump said migrants were “taking Black jobs now … they’re taking Black jobs and they’re taking Hispanic jobs”.

The remark was instantly controversial, the NAACP asking: “What exactly are Black and Hispanic Jobs!?!”

Harris’s jobs before becoming the first woman and first person of colour to be vice-president included district attorney of San Francisco, attorney general of California and US senator.

In Las Vegas, Biden told his audience: “It’s because of you that I’m president and Kamala Harris is vice-president. By the way, she’s not only a great vice-president. She can be president of the United States.”

The remark was not without attendant irony, given the continuing crisis in Democratic ranks over Biden’s age and cognitive fitness.

Since the Atlanta debate, in which the 81-year-old president appeared frail, struggled to offer coherent arguments and failed to counter Trump’s lies and invective, elected officials and party operatives have said Biden should step aside.

Nineteen House Democrats and one senator have called publicly for Biden to quit. On Tuesday it was reported that Adam Schiff, an influential California congressman running for US Senate, told donors Biden staying on the ticket could cost the party both houses of Congress as well as the White House.

Biden has rejected all such calls.

If he changed his mind, Harris would be the natural replacement but polling generally does not show her polling as well as other potential replacements in battleground states.

On Wednesday, Politico reported a memo from BlueLabsAnalytics, a Democratic-aligned firm, it said was circulating among those who want Biden to go.

Based on interviews with more than 15,000 voters in battleground states, the memo said, “alternative Democratic candidates run ahead of President Biden by an average of three points.

“Nearly every tested Democrat performs better than the president. This includes Vice-President Harris who runs better than the president (but behind the average alternative).”

According to the memo, the strongest potential Biden replacements in battleground states are Mark Kelly, an Arizona senator and former astronaut; Wes Moore of Maryland, only the sixth Black governor in US history; Josh Shapiro, the Pennsylvania governor whose response to the attempted assassination of Trump in his state has been widely praised; and Gretchen Whitmer, the Michigan governor widely held to be preparing a run in four years’ time.

In the aftermath of the Trump rally shooting, in which Trump was hurt in the ear while one supporter died and two were injured, Biden called for a cooling of campaign rhetoric.

He repeated the call in Las Vegas, but his speech still contained fiery lines.

Trump, Biden said, would “undo everything the NAACP stands for”. He also said “Donald Trump’s presidency was hell for Black Americans” and accused his opponent of “lying like hell”.

Biden’s mention of Harris produced a positive response – for Biden. The crowd chanted: “Four more years!”