Kamala Harris speaks at White House for first time since becoming presidential candidate

July 22 (UPI) -- Vice President Kamala Harris on Monday made her first public appearance since President Joe Biden endorsed her as his successor amid increased backing from prominent Democrats.

One day after she became a candidate, former Speaker of the House Nancy Pelosi endorsed her. And the Democratic caucus was expected to give its blessing to her candidacy.

On Monday afternoon, Harris appeared at a White House event celebrating NCAA Sports Day in front of athletes and Division I, II and III coaches who won championships over the previous school year.

Harris didn't address her candidacy as she served as a replacement at the event while Biden recuperates from testing positive for COVID-19 , in Delaware. Biden's symptoms "almost resolved completely," his physician Dr. Kevin O'Connor said in a letter Monday.

After the event at the White House, Harris traveled to Delaware to meet with campaign staff.

"Joe Biden's legacy of accomplishment over the past three years is unmatched in modern history," she on the South Lawn of the White House. "In one term, he has already surpassed the legacy of most presidents who have served two terms.

"I first came to know President Biden through his son, Beau. We worked together as attorneys-general in our states," Harris said.

"Back then, Beau would often tell me stories about his dad. He would tell me about the kind of father, and the kind of man that Joe is. The qualities that Beau revered in his father are the same qualities that I have seen every day in our president.

"His honesty, his integrity, his commitment to his faith and his family, his big heart and his love, deep love of our country -- and I am firsthand witness that every day our President Joe Biden fights for the American people and we are deeply, deeply grateful of his service to our nation."

Harris then spoke about the athletes.

"I know it was not easy to make it to this moment," Harris said. "Each of you has faced challenges and obstacles, and you have endured. You have fought back and fought through and by doing so, you demonstrated that true greatness requires more than skill. It requires grit and determination."

Harris herself is facing a historic task: becoming the first Black woman to become president, starting her effort just 105 days before the Nov. 5 election.

But first she must secure the Democratic nomination. The convention runs Aug. 19 to 22 in Chicago.

The Biden-Harris ticket earned 10% of the 3,896 pledged delegates during primaries and caucuses.

There also are 700 automatic "superdelegates," which include members of the House and Senate, governors, state party chairs and DNC members. They are not permitted to vote on the first ballot unless it's determined that one candidate has an absolute majority of pledged delegates.

On Friday , the party announced plans to conduct an early virtual roll call vote will not take place before Aug. 1 or after Aug. 7.

The Democratic committee that determines the rules for the party's nomination will meet Wednesday.

Pelosi's endorsement was seen as a valuable addition to Harris' stable of supporters.

"Today, it is with immense pride and limitless optimism for our country's future that I endorse Vice President Kamala Harris for president of the United States," Pelosi said in a statement posted on X . "My enthusiastic support for Kamala Harris for president is official, personal and political.

"Officially, I have seen Kamala Harris's strength and courage as a champion for working families, notably fighting for a woman's right to choose.

"Personally, I have known Kamala Harris for decades as rooted in strong values, faith and a commitment to public service.

"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."

Many Democratic governors and members of Congress have endorsed Harris, including potential running mates : Kentucky Gov. Andy Beshear, Pennsylvania Gov. Josh Shapiro, North Carolina Gov. Ray Cooper and Arizona Sen. Mark Kelly . None of them has said they want the job.

Colorado Gov. Jared Polis signaled an openness to being on the ticket with Harris.

"If they do the polling and it turns out that they need a 49-year-old, balding, gay Jew from Boulder, Colo., they got my number," Polis told CNN, after earlier calling the speculation "flattering."

Other prominent Democrat governors backing Harris include Gavin Newsom of California, Gretchen Whitmer of Michigan, J.B. Pritzker of Illinois andGov. Kathy Hochul of New York.

Small-dollar donors gave $81 million in the first 24 hours after Harris was endorsed, ActBlue said . That is the largest 24-hour total in presidential history, according to ActBlue.

Of the 880,000 "grass roots donors," 60% made their first contribution this year.

These totals include money raised "across the campaign, the Democratic National Committee and joint fundraising committees," ACTBlue said.

Future Forward, the major Democratic super political action committee, has secured $150 million in commitments from Democratic donors in the last 24 hours, a senior aide to Future Forward told CNN.

The group earlier this year reserved $250 million in digital and television ads to begin at the convention.

Harris traveled to Delaware on Monday afternoon to meet with members of the Delaware convention delegation and then appear at Biden's campaign headquarters in Wilmington.

"One day down. 105 to go. Together we're going to win," she posted on X on Monday morning .

J.D. Vance went to Middletown, Ohio , his hometown, for a rally Monday at the high school. On Monday night, he was scheduled to hold a rally in Radford, Va.

Former President Donald Trump 's next rally is planned Wednesday night in Charlotte, N.C.