'Strong political force': Biden campaign makes case for Kamala Harris 3 years after picking her for VP

President Joe Biden's campaign is making the case for Vice President Kamala Harris' spot on the Democratic ticket in a strategic memo to donors, supporters and political strategists obtained exclusively by ABC News, as she courts the party's base.

The document dated Friday defends the campaign's strategy of centering the vice president ahead of a tough reelection fight, describing her as someone who has proven to be a prolific fundraiser that connects with Democrats' voting base, and is critical to their success in the race.

"As we enter the heart of the 2024 cycle, Vice President Harris is positioned once again to be a strong political force and invaluable asset to the Biden-Harris reelection effort," according to the memo written by campaign manager Julie Chavez Rodriguez and senior adviser Becca Siegel, who oversaw the 2020 campaign's analytics.

In the next month, Harris will have a "big travel push" targeting young voters, a source with knowledge of the vice president's plans tells ABC News.

Young voters have proven to be an essential constituency for Democrats in 2020 and in the 2022 midterm elections, though many aren't yet sold on voting for Biden again.

At a young voters' summit in Washington, D.C., last month, most young voters told ABC News that climate change was their top issue in the election and that they felt the Biden administration was not doing enough to combat it.

Biden this week traveled out West to highlight his administration's efforts to protect the environment and announced a national monument near the Grand Canyon that would protect nearly a million acres of land and many Tribal Nation cultural sites.

The memo, sent exactly three years after Biden announced Harris as his vice-presidential running mate, comes as her approval rating among Americans is underwater. More, 52.3%, disapprove of her work compared to those who approve of it, 39.7%, according to a FiveThirtyEight polling average, though her net approval rating is an inch better than Biden's.

The memo instead highlights polling that shows Harris with positive marks among specific groups Democrats court in elections: non-White voters and low-income Americans.

"More important than any approval polling, however, is that the Vice President has established herself as a fearless voice on many of the issues that are most important to the core voters in the Biden-Harris coalition," Rodriguez and Siegel wrote in the memo.

Harris suffered a shaky start to her vice presidency. She faced a slew of staff turnover in her first year. And Biden tasked her with two priorities that were likely doomed from the start: Sorting out the root causes of migration amid surges of migrants arriving at the southern border, and ushering voting rights legislation through a near-evenly divided Congress, while contending with a filibuster requiring votes from Republicans.

Two years later, House Democrats' "For the People" voting rights legislation is not law, and migration continues to be a political issue for the Biden administration.

Republicans have mocked Harris for her early struggles with some GOP presidential candidates concentrating a heavy amount of their attacks around Harris. Former U.N. Ambassador Nikki Haley, for example, has repeatedly targeted Harris, suggesting Biden, America's oldest president, won't be in office for an entire second term. In Haley's GOP loyalty pledge, she crossed out Biden's name and wrote "President Harris" instead.

But Harris appears to be finding her footing in an attacker role she's recently taken on as part of the reelection campaign.

"Over the past few weeks alone, Americans have watched her be a powerful and effective messenger, calling out the extremist MAGA agenda and lifting up the issues that Americans care about: reproductive freedom, voting rights, economic opportunity, gun safety reform, and climate change and clean energy," the memo states.

Throughout the summer, Harris has traveled the country including a "blitz of large-scale events with key constituencies" of Black American and Latinos, and gun safety advocates that her vice-presidential staff announced last month. Those six stops included remarks before the NAACP convention and a speech Friday at gun-safety group Everytown's conference in Chicago. (Everytown and other gun-safety groups endorsed the Biden campaign earlier this week.)

She has also taken some notable previously unscheduled trips to take on political fights.

In July, just hours before Republican presidential candidates appeared on stage in Des Moines, Iowa, Harris traveled to the state to rail against abortion bans.

"As I travel the country, it becomes clear to me that so many people in these state legislatures don't even know how women's bodies work," Harris told a mostly female audience.

"One does not have to abandon their faith or deeply held beliefs to agree the government should not be telling her what to do," Harris later added.

Iowa Republican Gov. Kim Reynolds signed an abortion ban into law just weeks before Harris' visit.

"We read in Scripture that the Author of life wants to give 'a future and a hope' to all his children and who are we to stand in His way," Reynolds said minutes before signing the bill into law.

A federal judge temporarily blocked the law three days after it was enacted.

The Biden campaign sees abortion as a winning issue for them, pointing to multiple referendums on the issue that have gone their way, including in Ohio on Tuesday.

Harris also took a swiftly planned trip to Jacksonville, Florida, last month to criticize proposed Black history curriculum the state's board of education unanimously approved. The new standards' "benchmark clarifications" included a call for instructing students about "how slaves developed skills which, in some instances, could be applied for their personal benefit."

The vice president, while on a pre-scheduled trip to Orlando a week later, took the opportunity to again attack the proposal.

DeSantis has defended his state's Black history curriculum, though he said he was not involved in its creation. The governor invited Harris to Florida to debate the issue. She declined the invitation.

The campaign sees the nation's first female, Black and South Asian vice president's latest engagements as proof that she is "a uniquely effective messenger capable of calling out [Republicans'] attacks," according to the memo.

Harris has also been on the fundraising circuit for the Biden campaign, raising money from deep-pocketed donors around the country, as the campaign looks to stuff its coffers in the early months of what is likely to be another expensive election.

Already in the third quarter, Harris has headlined three fundraisers with two more planned on Martha's Vineyard on Saturday and one in Seattle on Wednesday. The campaign said Harris is on track to hold more fundraisers in the third quarter than Biden.

The Biden campaign may be hoping for fundraising success similar to when Harris was announced as Biden's running mate in 2020. In the first day after that announcement, Democrats raised more money than any other 24-hour period ever, the campaign said, a sign of excitement among their base for the vice president.