CHICAGO — Vice President Kamala Harris has spent much of the past two days holed up with a small group of top aides in the Park Hyatt hotel, just blocks from Lake Michigan, refining and practicing the most important speech of her political career.

When Harris takes the stage at the Democratic National Convention on Thursday night, she will aim to introduce herself to a nation that remains largely unfamiliar with her life story, people familiar with the speech prep process said, requesting anonymity to discuss a confidential process. Her lightning-fast ascent to the top of the Democratic ticket means she has not faced the usual array of primaries and debates that let voters get to know a presidential nominee, and a major goal of Thursday’s speech is to help remedy that gap.

Since Biden dropped out of the presidential race and endorsed Harris, her public appearances have stayed largely the same: big rallies in swing states with a nearly identical stump speech. The themes are expected to remain the same on Thursday, but aides said Harris will dive more deeply into her personal story and try to connect it to her policies and vision for America.

“She’s the vice president,” said Jamal Simmons, Harris’s former communications director in the White House. “People haven’t paid as much attention to all the details of her life. The president is the politician that we know the best, so she’s got to make sure that she tells people who she is before Donald Trump has a chance to tell them.’

Adam Frankel, who was a speechwriter on former president Barack Obama’s 2008 presidential campaign and then joined his White House, has been taking the lead on writing the speech with Harris, according to two people familiar with the process. Frankel temporarily joined Harris’s vice presidential office during the first year of her tenure as a senior adviser.

Harris’s two chiefs of staff — Lorraine Voles, at the White House, and Sheila Nix, on the campaign — have also been deeply involved in the process in recent days, as Harris has balanced her public events, including a surprise appearance at the Democratic National Convention on Monday night, with her work on a speech that is crucial to her efforts to sustain the energy of her campaign.

For Harris, the speech will cap a remarkable stretch during which she consolidated support in the Democratic Party behind her presidential bid, took over Biden’s campaign apparatus in Wilmington, Del., selected Minnesota Gov. Tim Walz as her running mate and debuted a new campaign message tailored to her background and experience. Now, with fewer than 80 days until Election Day, Democrats will look for Harris to keep up the momentum and set the tone for a two-month blitz to Nov. 5.

Yet unlike such figures as Barack Obama and Bill Clinton, Harris has never been known for soaring oratory. Her strength, rather, has come in smaller moments that play to her prosecutorial abilities–questioning a witness as a senator or firing off a zinger at an opponent during a debate. Still, many Democrats say that her rallies since becoming the likely nominee have showcased a greater comfort with her role.

Harris will detail her upbringing and professional career in California, highlighting parts of her biography — particularly her time as a prosecutor — that she sought to downplay when she ran for president in 2019, in a vastly different political landscape. In particular, Harris is expected to remind voters of the types of cases she worked on, including prosecuting transnational gangs, sexual assault cases and foreclosure misconduct, according to the people familiar with the prep process.

Harris, who grew up in a middle-class family in California, is expected to frame her ascent to the pinnacle of politics as a uniquely American story, leaning into a patriotic frame she will contrast with Republican nominee Donald Trump, who Democrats argue is more concerned about his own interests than those of the nation.

But California Gov. Gavin Newsom, who has known Harris for decades, said voters will also be looking for Harris to lay out a vision for where she wants to take the country and what she hopes to do as president.

“It’s about a future where you feel respected, connected to that future, and you feel that people are listening to you, and you’re being heard,” Newsom said. “And so I think if she does that, it will be a grand slam.”

As Harris prepares, Newsom said she faces both the privilege and pressure of an enormous platform. “She’s tough,’ he said. “She’s disciplined. She is very, very skilled, and I have no doubt she’ll land on Thursday night.”

The speech may get particular attention because Harris’s campaign has been so short that every event—from debates to rallies to the convention itself—rises to an outsize level of importance. It’s sharp contrast with Biden in 2020, who’d already had a grueling primary, and a half-century in politics, to introduce himself to voters.

Harris ascended to the top of the Democratic ticket almost overnight when Biden withdrew from the presidential campaign on July 21 and endorsed her. While Harris ran a brief presidential primary campaign in 2020 and has served as vice president for more than three years, neither experience resulted in sustained high-profile exposure, and both parties have been scrambling to fill that vacuum.

Republicans are portraying the vice president as an out-of-touch liberal, and Trump has gone further, depicting her as a somehow foreign, elusive figure. Democrats are racing to cement her image as a middle-class American who was a tough but compassionate prosecutor—an image she hopes to flesh out on Thursday night.

Harris is expected to tie her biography to policy ideas, such as her recently announced plan to hold down food prices, contending that she understands the middle class in a way that the wealthy Trump does not. The inflation that has upset so many voters also raises the pressure on Harris to show she understands how high prices hurt Americans.

At recent campaign events, Harris has given previews of the way she may talk about her life story.

“I grew up in a middle-class household. For most of my childhood, we were renters,” Harris told an audience at an Aug. 16 rally in Raleigh, N.C.. “My mother saved for well over a decade to buy a home. I was a teenager when that day finally came, and I can remember so well how excited she was.”

She also described working at McDonald’s as a young person to earn spending money. “Some of the people I worked with were raising families on that paycheck,” Harris said. “They worked second or even third jobs to pay rent and buy food. That only gets harder when the cost of living goes up.”

As Harris has shed her more liberal stances — disavowing Medicare-for-all, reversing her support to ban fracking and clarifying she would not abolish Immigration and Customs Enforcement agency — she has worked to emphasize her prosecutor background to contrast her record with Trump, now a convicted felon.

While Biden largely shied away from discussing all of Trump’s legal troubles, worried about the optics of weighing in while his Justice Department was pursuing some of the cases, Harris has leaned in, arguing her experience taking on fraudsters, cheaters and predators has prepared her to defeat Trump.

“Hear me when I say I know Donald Trump’s type,” Harris has often repeated at rallies over the last month. “I know the type. And I have been dealing with people like him my entire career.”

Since Harris took over Biden’s campaign, Trump has launched a variety of attacks on Harris, though he has struggled to stay on a consistent message, much to his aides and allies’ frustration. He has attacked her gender and race, openly questioning her racial identity and making crude comments about her appearance.

Trump’s allies say they want him to focus on policy differences rather than personal attacks, arguing that the former president has the opportunity to define the vice president based on her more liberal policy positions while running for president in 2019.

“This is a different kind of a race,” Trump said last week. “All we have to do is define our opponent as being a communist or a socialist or somebody that’s going to destroy our country.”