Kamala Harris was closing in on the Democratic party’s presidential nomination on Monday after the former House speaker, Nancy Pelosi, joined a slew of Democratic heavyweights endorsing her run for the White House – and Harris gave a rousing evening speech to campaign staff, with Joe Biden calling in by phone to support her.

While Harris’s nomination still has to be officially confirmed by Democratic party delegates at or before their national convention in Chicago next month, Pelosi’s endorsement, which she said was “official, personal and political”, effectively clears the way for the vice-president to become the nominee after Biden announced on Sunday he would not seek re-election.

“I have known Kamala Harris for decades as rooted in strong values, faith and a commitment to public service,” Pelosi’s statement said.

“Politically, make no mistake: Kamala Harris as a woman in politics is brilliantly astute – and I have full confidence that she will lead us to victory in November.”

The backing of Pelosi, a hugely influential veteran Democratic figure, was the most prominent of a cascade of endorsements Monday from a broad array of allies.

On Monday afternoon, what has now become the Harris presidential election campaign announced an all-time record fundraising in the first 24 hours of a candidacy, bringing in $81m from hundreds of thousands of donors, most of whom were giving for the first time in this election.

Then Harris went to what had been originally set up as the Biden-Harris re-election campaign headquarters in Wilmington, Delaware, to talk to campaign staff.

Biden, who is recovering from Covid-19 at his house in Rehoboth, Delaware, spoke by phone to the staff first, saying he would be out on the campaign trail for Harris and adding: “I’ll be doing whatever Kamala Harris wants me or needs me to do.”

When Harris took the microphone to address staff, Biden said to her: “I love you, kid.” Harris put her hands on her heart and said: “I love you, Joe.”

Then, appearing buoyed with a new confidence, she said it was her intention to “earn and win” the party’s nomination for president and added “we are going to take our case to the American people and we are going to win”.

She said, to cheers, that as a former prosecutor, running against Republican nominee Donald Trump, a convicted felon who has also been found liable for sexual abuse by a jury, “I know Donald Trump’s type” and she would “proudly put my record against his”.

If she wins the nomination and the White House she said she would put building up the US middle class at the center “of my presidency”, along with other priorities including gun control and reproductive rights.

Hakeem Jeffries, the House minority leader, and Chuck Schumer, the Senate majority leader, were both expected to follow Pelosi’s lead and endorse Harris soon.

Meanwhile, support came from inside Congress and beyond, with politicians, unions and other allies lining up. Significant endorsements came from the Democratic governors of Illinois, Michigan, Minnesota and Wisconsin, four battleground midwestern states seen as essential milestones on the pathway to the White House.

Two of them, Gretchen Whitmer of Michigan, and JB Pritzker of Illinois, had been mentioned as possible challengers to Harris for the nomination. Their blessing for her candidacy, along with that of Kentucky’s Andy Beshear, which also came on Monday, leaves a dwindling potential field.

Beshear is thought to be a leading candidate for Harris’s running mate if she wins the nomination, a shortlist that reportedly included the Pennsylvania governor, Josh Shapiro; Arizona senator Mark Kelly; and North Carolina governor, Roy Cooper.

All swiftly issued statements expressing their support for Harris’s presidential run.

On Monday morning, Harris had given her first speech since Biden withdrew from the race, standing in for him at a White House event celebrating student athletes.

“Joe Biden’s legacy of accomplishment over the past three years is unmatched in modern history,” she said, paying tribute to his “deep love of our country” but avoiding talk of her own candidacy at that point.

Eyes now are on Barack Obama, who on Sunday paid tribute to Biden, his vice-president though two terms of office, whom he reportedly helped push from the race.

“We will be navigating uncharted waters in the days ahead,” Obama said in a statement. “But I have extraordinary confidence that the leaders of our party will be able to create a process from which an outstanding nominee emerges.”

Harris remains in a strong position, further bolstered by other senior Democrats on Monday including the Massachusetts senator Elizabeth Warren, who ran for the nomination in 2020; the Maryland governor, Wes Moore; and the Illinois senator Dick Durbin, the chamber’s majority whip.

In a tweet on Sunday night, the New York congresswoman Alexandria Ocasio-Cortez also pledged her “full support” to ensure Harris’s victory in November, saying she “will be the next President of the United States”.

Last week she had warned of “chaos” if Biden was deposed and claimed that a large number of those who wanted him out “do not want to see [Harris] be the nominee”.

Biden threw his support behind Harris, saying that choosing her as his vice-president was “the best decision I’ve made”. His campaign finance account changed its name to “Harris for President”, unearthing a $96m cash war chest for the vice-president to make her case to American voters.

She won endorsements from the leadership of several influential caucuses and political organizations, including the chairs of the Congressional Progressive caucus and the Congressional Hispanic caucus and the entire Congressional Black caucus.

Harris, if elected, would be the first woman and first person of South Asian descent to be president.

The rounds of endorsements followed weeks of clamoring on the left and social media memes pushing for Harris’s rise. Her supporters, dubbed the “KHive”, shared coconut emojis, a nod to a speech in which she laughed about something her mother used to say: “You think you just fell out of a coconut tree? You exist in the context of all in which you live and what came before you.” They resurfaced an ad from Harris’s 2020 presidential bid that attacked Trump for his comments on women and questionable businesses and posted copies of a check Trump made to Harris’s previous campaigns in California.

No coordinated opposition has emerged against Harris or in favor of any other candidate, a sign that Harris will probably be able to win the presidential nomination. The California governor, Gavin Newsom, another floated as a possible contender, said Sunday he would be endorsing Harris.

The Democratic National Committee chair, Jaime Harrison, has said the party would soon announce the next steps in its nomination process.

Reuters and the Associated Press contributed to this report

Read more about Joe Biden dropping out of the 2024 election: