On Saturday afternoon, US Vice-President Kamala Harris sat on stage at a black cultural festival in New Orleans, talking about her life story and what she felt she had achieved in the White House.

It was the kind of event that the first female, black and South Asian American vice-president has regularly attended throughout her three-and-a-half years as Joe Biden’s deputy, usually trailed by a small press pack dwarfed by that which follows the president himself.

But as panicked Democrats a thousand miles away in Washington weighed replacing 81-year-old Joe Biden as the party’s candidate for November’s election following his woeful and sometimes incomprehensible debate performance against Donald Trump, the number of reporters trailing Ms Harris had swelled to dozens.

On stage and through her travels this weekend, the vice-president did not address swirling questions about Mr Biden’s fitness for office and whether he should withdraw and hand the baton to her.

But in discussing ambition and how to forge your own path with her audience in New Orleans, she encouraged the crowd not to listen to naysayers.

“People in your life will tell you, though, it’s not your time. It’s not your turn. Nobody like you has done it before,” she said. “Don’t you ever listen to that.”

Since the disastrous CNN debate on 27 June, she has repeatedly defended her boss, arguing that his record as president shouldn’t be outweighed by 90 minutes on a debate stage. Mr Biden himself has struck a defiant tone and fiercely insisted that he will remain the nominee.

Yet as calls grow louder for the president to step aside, some high-profile Democrats are unifying behind 59-year-old Ms Harris as the natural candidate to replace him.

On Sunday, congressman Adam Schiff of California told NBC’s Meet The Press that either Mr Biden had to be able to “win overwhelmingly or he has to pass the torch to someone who can”. Kamala Harris, he added, could “very well win overwhelmingly” against Trump.

That’s a proposition that has raised eyebrows among some Democrats, including Biden allies, who see in Ms Harris a vice-president who failed in her bid for the 2020 Democratic nomination before the first ballot was even cast and who has struggled with an uneven record and low approval ratings throughout her time in the White House.

Against that, senior Democratic lawmakers like Mr Schiff and South Carolina congressman Jim Clyburn have been floating Ms Harris as the obvious successor should Mr Biden ultimately bow to party pressure.

Supporters point to a handful of polls that suggest she would perform better than the president in a hypothetical match-up against Donald Trump, and they argue she has the national profile, campaign infrastructure and appeal to younger voters that could make the transition seamless four months before election day.

An elevation to the top of the ticket would be a remarkable turnaround for a woman not long ago seen as a political weakness by senior figures in the Biden White House. Even Mr Biden himself reportedly described her as a “work in progress” during their first months in office.

But Jamal Simmons, a longtime Democratic strategist and Harris’s former communications director, said she had long been underestimated.

“Whether she’s a partner to the president or she has to lead the ticket, she is somebody who Republicans and the Trump campaign need to take seriously,” Mr Simmons told the BBC.

Since the debate and its fall-out, Ms Harris has altered her schedule to stick close to the president. She appeared at a heavily-scrutinised meeting last Wednesday where Mr Biden sought to reassure powerful Democratic governors about his fitness for office.

And a day later, on the Fourth of July – America’s Independence Day – she abandoned her usual tradition of grilling hotdogs for firefighters and Secret Service agents at her Los Angeles home to be by Mr Biden’s side at the White House celebrations.

The former top prosecutor has focused on criticising Trump in public appearances since the debate, pressing the case as to why voters should believe he is a threat to democracy and women’s rights. At the same time, she has offered nothing but steadfast support for Mr Biden.

Vice-presidents always need to strike a delicate balancing act between ambition and loyalty, but Ms Harris knows that this is not a moment where she can show any daylight between her and the president.

Over the past week multiple Democratic Party operatives, some of them anonymously and some of them under their own names, have begun publicly pushing the narrative that Kamala Harris shouldn’t be Joe Biden’s running mate because she’s too “ambitious” or cut-throat.

Joe Biden has a number of strong choices for running mate, and I trust him to make the pick that he thinks will be best for his administration and for the nation. Apparently some of these political operatives don’t trust Biden, because they think he’s going to pick Kamala Harris – and they’re so dead set against it, they’re leaking horrible sentiments about her.

Let’s be clear here. Everyone who wants to be President or Vice President is “ambitious” by definition. But you only hear that word used negatively in politics when it’s in reference to a woman or a person of color. This backlash against Kamala Harris, simply for being a highly qualified person who wants to move up the ladder, is sexist and racist in nature. It needs to stop.

In addition to the sexism and racism on display here, this is also yet another instance of liberals and Democrats falling into the “anyone but the frontrunner” trap. Most observers think Kamala Harris is the frontrunner for VP, and so some people have decided that it should be anyone but her, because frontrunners are somehow inherently bad. We see this nonsense every primary season, where Democrats start bandwagoning on in favor of anyone they can find, just so they can feel good about not having to support the frontrunner. It’s harmful and stupid, and it costs us elections, and it needs to stop too.

Joe Biden’s pick isn’t going to be influenced by this kind of anti-woman, anti-minority, or anti-frontrunner idiocy. He has plenty of strong choices. The contenders have all conducted themselves with honor. Biden will pick whoever he picks. It has to be his decision in the end. The other contenders will all support Biden’s pick. But some of the political operatives floating around the edges of this process sure are revealing an ugly side of themselves.