Two in three Americans in the new survey, which was conducted using Ipsos' KnowledgePanel, are familiar enough with her to form an opinion, and among those who do, she's viewed slightly more positively than negatively -- a significant accomplishment at a moment of deep political divide and animosity towards the nation's leaders.
Harris, who is less well-known than the three men, has a favorability rating of 35%, while 31% view her unfavorably. Her favorability soars to 71% among Democrats.
That number among Black Americans, a core constituency of the party's base, stands at 52% but a large portion, roughly 40%, doesn't know enough about her to rate her or had no opinion of her.
For Biden, a slightly higher 40% of Americans view him favorably, compared to 43% who have an unfavorable perception of the former vice president.
Biden also earns positive marks for his decision to place Harris on the ticket, with an equal 40% of Americans both approving of the decision and viewing his decision-making favorably for it. Only 23% disapprove of the move and 26% see the choice as a negative reflection of his ability to make important decisions.
He acknowledged the gravity of his decision when he announced his pick, which 44% of Americans consider to be excellent or good in the new poll, compared to only 28% who rate his choice of Harris as not so good or poor.
"You make a lot of important decisions as president. But the first one is who you select to be your Vice President. I've decided that Kamala Harris is the best person to help me take this fight to Donald Trump and Mike Pence," Biden wrote in an email to supporters.
Biden announced on Tuesday that he asked Harris to be his running mate -- a historic choice that culminated a months-long process that largely took place in secret. She is the first Black woman, the first person of Indian descent and the third woman in history to be selected to be a vice presidential running mate.
Throughout the vice presidential search, Biden repeatedly insisted he was looking for someone who would be "simpatico" with him in their vision of leadership and agenda, and would be ready to step into the role of president "on day one."
The new poll finds that Americans are more likely to believe that Harris is qualified for the nation's highest office than not.
Four in 10 Americans, and 43% of registered voters, believe that the former California attorney general, who was first elected to the Senate in 2016, is qualified to assume the role of president if necessary -- a potentially more salient reality for the Biden-Harris ticket because if Biden is elected in November, he will be the oldest first inaugurated president in the country's history at the age of 78. Only 32% of Americans and 33% of registered voters don't think she would be qualified to serve as president.
Before Harris was selected, there was some angst among those on the left about her tough-on-crime record in law enforcement, despite Harris describing herself as a "progressive prosecutor." She was the San Francisco district attorney from 2004 to 2011, before becoming California's attorney general, a position she held from 2011 to 2017. Aspects of her career were under intense scrutiny throughout the primary, particularly among her more liberal opponents, who believed her progressive posture on the campaign trail did not reflect in her prosecutorial record.
After the campaign where she was cast as too far to the right on criminal justice issues, 9% of Americans, and 8% of registered voters, view Harris as too conservative.
That number ticks up to 13% among Democrats, to 15% among Black Americans and to 18% among Hispanics.
Harris and Biden's relationship was tenuous at times throughout the primary, after she criticized him on his record on race at the early debates. But he embraced his one-time rival -- who was seen as more middle-of-the-road in the primary and has already been a difficult target for the president and his campaign to define.
As the GOP ticket adjusts to their new rival, Harris' marks in the new poll also show more public confidence in her than her Republican counterpart.
By an eight-percentage-point margin, Americans are more likely to believe in Harris' ability to step into the role of president, compared to a two-percentage-point margin for Pence.
Harris is also considered far more inspiring among Americans than Pence, 40% to 28%. Historically, too, she is more well-known at this stage of the cycle than recent vice presidential picks, boasting higher national recognition than Pence and Sen. Tim Kaine, D-Va., according to a 2016 ABC News/Washington Post poll.
Pence is consistently viewed in a more negative light across every quality polled, including sharing their values: 35%-46%, caring about people like them: 35%-45% and being honest and trustworthy: 38%-42%. Meanwhile, net attitudes about Harris are more positive, with more people than not believing she shares their values: 36%-35%, cares about people like them: 38%-33% and is honest and trustworthy: 39%-30%.
With less than three months until Election Day, the focus on the electorate will likely shift to potentially moveable voters who could tilt the scales of the election. In 2016, one key voting bloc was those who opposed both candidates and more of that group ultimately swung toward Trump over Hillary Clinton. This year, among this group, which makes up 10% of the population in this poll, Harris is also more well-received than Pence.
This ABC News/Ipsos poll was conducted by Ipsos Public Affairs' KnowledgePanel® August 11-12, 2020, in English and Spanish, among a random national sample of 1,044 adults. Results have a margin of sampling error of 3.3 points, including the design effect. See the poll's topline results and details on the methodology here.
This report was featured in the Thursday, Aug. 13, 2020, episode of “Start Here,” ABC News’ daily news podcast.
"Start Here" offers a straightforward look at the day's top stories in 20 minutes. Listen for free every weekday on Apple Podcasts, Google Podcasts, Spotify, the ABC News app or wherever you get your podcasts.