Democratic presidential candidate Joe Biden named Senator Kamala Harris as his vice-presidential pick on Tuesday, ending weeks of speculation over who his running mate will be in the November US election.

“I have the great honor to announce that I’ve picked @KamalaHarris – a fearless fighter for the little guy, and one of the country’s finest public servants – as my running mate,” Biden posted on Twitter.

The 55-year-old California senator is the first Black woman on a major presidential ticket in US history. Biden had earlier made it clear that he would choose a woman for the role, with Harris and Susan Rice, former national security adviser to President Barack Obama, considered top contenders.

With social unrest over racial injustice and police brutality against Black Americans rocking the country for months, Biden had been under increasing pressure to select a woman of colour as his running mate. Harris is also the first Asian-American on a major presidential ticket: her mother was born in India.

Also under consideration were congresswoman Karen Bass of California, Senator Elizabeth Warren of Massachusetts, congresswoman Val Demings of Florida, Michigan Governor Gretchen Whitmer and Senator Tammy Duckworth of Illinois.

“@JoeBiden can unify the American people because he's spent his life fighting for us. And as president, he'll build an America that lives up to our ideals,” Harris tweeted. “I'm honored to join him as our party's nominee for Vice President, and do what it takes to make him our Commander-in-Chief.”

Biden and Harris will make their first joint appearance as a presidential ticket on Wednesday in his hometown of Wilmington, Delaware, the campaign said.

The United States has never had a woman vice-president, and the move comes four years after the country’s first female presidential nominee from a major party, Hillary Clinton, lost her White House bid.

“Back when Kamala was Attorney General, she worked closely with Beau. I watched as they took on the big banks, lifted up working people, and protected women and kids from abuse. I was proud then, and I'm proud now to have her as my partner in this campaign,” Biden said on Twitter.

The former vice-president was referring to his late son, Beau Biden, who had served as the attorney general of Delaware. Harris was previously California’s attorney general. She is well known for her sometimes aggressive questioning style in the Senate, most notably of Brett Kavanaugh during his 2018 Supreme Court confirmation hearing.

“To see a Black woman nominated for the first time reaffirms my faith that in America, there is a place for every person to succeed no matter who they are or where they come from,” said US congresswoman Val Demings, who is Black and was also considered as Biden’s running mate.

The stakes for Biden’s vice-presidential pick are high, as his age has been a main target for President Donald Trump, who has attempted to raise doubt on his cognitive ability.

Trump’s campaign immediately criticised Harris, mocking her as the 77-year-old Biden’s “political living will” in a statement.

“In her failed attempt at running for president, Kamala Harris gleefully embraced the left’s radical manifesto,” said Katrina Pierson, campaign senior adviser for Trump, 74. “She is proof that Joe Biden is an empty shell being filled with the extreme agenda of the radicals on the left.”

The president himself was quick to respond to the announcement on Tuesday, tweeting a video that labelled his opponents “Slow Joe” and “Phoney Kamala”.

Trump said he was “a little surprised” that Biden selected Harris as his running mate, saying she had been “nasty” to the former vice-president in primary debates.

“She was my number one pick” to run with Biden, Trump said at a Tuesday news conference.

Trump attacked Harris for her questioning of Brett Kavanaugh over sexual misconduct allegations during his Senate confirmation hearings to join the Supreme Court.

“I thought she was the meanest, the most horrible, the most disrespectful of anybody in the U.S. Senate,” Trump said.

Earlier on Tuesday, Trump had criticised his rival’s vice-presidential selection process, saying that some men are “insulted” by Biden’s decision to promise to select a woman as his running mate.

In an interview with Fox Sports Radio, Trump said: “I would be inclined to go a different route than what he’s done”, indicating that Biden “roped himself off into, you know, a certain group of people”.

Of Biden’s vow to choose a woman, Trump said: “Some people would say that men are insulted by that. And some people would say it’s fine”.

Biden campaign spokesperson Andrew Bates said Trump was “easily threatened”.

“And because of his insulting negligence and erratic, failed leadership, over 5 million Americans have been infected with coronavirus, over 160,000 died, and tens of millions remain jobless,” Bates said in a statement.

Former Republican vice-presidential nominee Sarah Palin congratulated Harris - and offered some advice on how best to fill the role.

“Congrats,” Palin wrote in an Instagram post. “Climb upon Geraldine Ferraro’s and my shoulders, and from the most amazing view in your life consider lessons we learned.”

A former Alaska governor, Palin was John McCain’s running mate in 2008. Democrat Ferraro ran with Walter Mondale in 1984.
Palin’s post included a series of tips for Harris, including “trust no one new,” “fight mightily to keep your own team with you,” “don’t get muzzled” and “don’t forget the women who came before you”.

She also warned Harris that “yahoos running campaigns will suffocate you with their own self-centered agenda“ and urged Harris to “stay connected with America as you smile and ignore deceptive ‘handlers’ trying to change you”.

McCain and Palin were defeated in 2008 by Barack Obama and his running mate, Biden.