The prosecutor vs. the felon. Democrats see winning contrast between Harris and Trump.

"I know Donald Trump's type," Vice President Kamala Harris said Monday to cheers at her first stop as a presidential candidate.

Speaking to staff and supporters at her campaign headquarters in Delaware, Harris cast herself, as she has before, as a tough prosecutor with a winning record prior to becoming a Washington politician.

"Before I was elected as vice president, before I was elected as United States senator, I was elected attorney general, as I've mentioned, to California," she said. "Before that, I was a courtroom prosecutor. In those roles, I took on perpetrators of all kinds."

"Predators who abused women, fraudsters who ripped off consumers, cheaters, who broke the rules for their own gain," Harris continued. "So, hear me when I say I know Donald Trump's type. And in this campaign, I will proudly put my record against his."

She used the same, well-timed attack line against Trump -- almost word for word -- at her first rally in battleground Wisconsin on Tuesday, where it again garnered applause and even chants of "Lock Him Up!"

As Democrats rallied around Harris in the 24 hours after Biden's stunning announcement he would not seek reelection, her prosecutorial background has generated party enthusiasm as a stark point of contrast against Trump, who was convicted of 34 felony counts in May.

Trump is set to be sentenced in his criminal hush money case in New York on Sept. 18, which will be in the height of the general election campaign. The former president has vowed to appeal the guilty verdict.

"It's a beautiful split screen," said Maria Cardona, a Democratic strategist and former senior adviser to Hillary Clinton and former communications director for the Democratic National Committee.

"She went after bad people who hurt the people that she was representing and that's exactly what she's doing now," Cardona said of Harris.

Harris was elected San Francisco District Attorney in 2004 and several years later became California's attorney general. She was the first female, Black and South Asian attorney general in the state's history.

Brian Brakow, who managed Harris's 2010 attorney general campaign, said Democrats should lean into the narrative of Harris representing the rule of law and that her prosecutorial background could give her a big advantage in a presidential campaign.

"I think she learned to be tough as nails," he said. "She is someone who prepares and takes her job responsibilities very seriously. I mean, when you're a prosecutor, one little mistake can cost you a verdict. And so she's somebody who has always done the work and not shied away from tough fights or tough opponents."

Those skills served her well in the Senate, where she frequently made headlines for her forceful questioning of Trump officials and court nominees appearing before her and the Senate Judiciary Committee.

Supreme Court Justice Brett Kavanaugh froze for several seconds when Harris pressed him about reproductive rights during his confirmation hearing, asking him: "Can you think of any laws that give government the power to make decisions about the male body?" The moment made the rounds on late night shows and on social media.

"If you look at why she ran for president in the first place, it's because she was a star in the Senate in that environment where she's having an adversarial conversation with someone across the witness stand," said Jim Kessler, the co-founder of center-left think tank Third Way.

But much of that style was lost in her first years as vice president as she struggled to find her footing and reports of dysfunction plagued her office. At one point not too long ago, columnists and pundits questioned whether Biden should drop her from the ticket.

Both Cardona and Brakow attributed her early stumbles to the inherent complications involved in being number two to the president, noting she took on tough tasks on politically unpopular issues like immigration -- which Republicans continue to attack her over, claiming she failed as "border czar" when, in fact, she was assigned to address the root causes of migration in Central and South America.

"I think she came away from those assignments with some bruises, but also a lot of valuable experience and knowledge," Brakow said.

After Roe v. Wade was overruled, though, Harris seemed to find her stride as the face of the administration's fight for reproductive rights and abortion access, traveling the country to speak forcefully on the issue. Earlier this year, she visited an abortion clinic in Minnesota, a trip believed to be the first of its kind for any president or vice president.

"I think she's been unleashed," said Cardona.

Going forward, strategists stressed Harris not only needs to make the case against Trump but also for the agenda and achievements of the Biden administration -- two issues Democrats were most concerned Biden wouldn't be able to communicate forcefully enough on the trail after seeing his poor debate performance against Trump.

"I think this is phase one, where they're going to show her as that prosecutor and make the case against criminal Donald Trump that maybe some folks feel Biden didn't think strongly enough," Kaivan Shroff, a Democratic strategist, said on ABC News Live.

"But they're also going to have a different phase of this campaign, and I think they're going to be somewhat concurrent, which is making the case on policy: the wins of the Biden-Harris administration and what is on the table. She's going to be talking about Roe, she's going to be talking about Project 2025," referring to the conservative blueprint for a second Trump term she has called extreme.

The Trump campaign is already pivoting their attacks toward Harris, who they argue "owns all of the bad policies of the Biden administration."

Many Republicans, including Trump campaign spokesperson Steven Cheung, are trying to paint her as "soft on crime" through her record as attorney general implementing some criminal justice reforms and more recent support for bail reform.

Harris defended her record as being "smart on crime" during her 2020 campaign, when she faced not only Republican attacks but also criticism from progressives who said she was too tough on issues like the death penalty or her anti-truancy program.

Recently, Trump himself has taken to amplifying his success in delaying his other legal cases and adding Harris to his attacks on the justice system.

"All of these Biden/Harris cases against me are a Weaponization of Justice against their Political Opponent, Me," Trump wrote on his social media site on Monday.