In her speech, aides and advisers said Harris, 59, planned to tell the story of who she was – the daughter of a Jamaican father and Indian mother – and of her plans to help the middle class with cuts in prices on groceries and housing and in taxes and to advance personal freedoms including abortion rights.
They said she would also deliver a robust denunciation of her Republican rival, former president Donald Trump.
“There is a guy who wants to divide us and she will make the case that we simply cannot let that happen, that this is America and everybody can rise together,” Cedric Richmond, campaign co-chair and longtime adviser to Harris, told Reuters.
Convention delegates got a preview when Harris unexpectedly walked out on stage to the tune of Beyonce’s Freedom on the convention’s first night.
“This November we will come together and declare with one voice, as one people – we are moving forward,” she said.
Whether Beyonce will appear on stage at the convention is a matter of much speculation and debate in convention hallways and meeting places.
The campaign declined to comment.
Harris has raised a record-breaking US$500 million (NZ$814m) in a month, and narrowed the gap or taken the lead against Trump in many polls of battleground states.
But the US vice-president has yet to articulate much of her vision for the country.
Enthusiasm and rising poll numbers are not enough to beat Trump in 11 weeks, strategists warned.
Harris is leading in a compilation of national polls by 46.6% to Trump’s 43.8%, and has pulled ahead in several public battleground state polls. However, the race remains tight.
Earlier this week, the founder of the main outside spending group backing Harris’ presidential bid said internal polling was less “rosy” than public polls suggested and warned Democrats faced much closer races in key states.
Harris has spent weeks on the speech, making changes to drafts from lead speechwriter Adam Frankel, including during campaign trips on Air Force Two.
Her focus on what she has called “price gouging” has drawn criticism from Republicans who say Democrats should trust free markets rather than set prices.
“She will highlight her message on prices because that is resonating really well with people, despite Republican attacks,” an aide to the vice-president said.
The speech will include elements of foreign policy along with stories of women affected by abortion bans and other curbs on reproductive rights, the aides and advisers said.
It will also include a nod to such allies as unions and lean on Republican voices to persuade conservative voters to abandon Trump.
Former US representative Adam Kinzinger, one of the 10 House Republicans who voted to impeach then-president Trump, said he would speak at the convention, one of several Republicans disenchanted with Trump to address the gathering.