US Vice-President Kamala Harris, having now secured backing from Congress' top Democrats, held her first presidential-style campaign rally in Wisconsin on Tuesday, where she sharply criticized the Republican nominee Donald Trump.

Harris continued to bolster her political support Tuesday after announcing that she also had secured pledges from enough party delegates to secure the Democratic nomination for president.

Harris, 59, had moved quickly to shore up her likely nomination after President Joe Biden, 81, on Sunday announced that he would not seek reelection. Biden endorsed Harris that day, and the vice-president's campaign picked up steam.

Most Democratic lawmakers have lined up behind her candidacy, including the party's leaders in the Senate and House, Chuck Schumer and Hakeem Jeffries, who endorsed Harris on Tuesday at a joint press conference. Former House speaker Nancy Pelosi endorsed Harris on Monday.

Democrats were looking to unify the party following a tumultuous month of infighting over whether Biden should remain the nominee.

An Associated Press unofficial survey found that Harris has the support of 3,095 delegates from various states — 1,976 are needed for the nomination. Delegates still may vote for the candidate they prefer when the party picks its new nominee next month at the Democratic National Convention in Chicago.

"This campaign is not just about us versus Donald Trump. This is about who we fight for," she said before an enthusiastic audience Tuesday at a high school in West Allis, a Milwaukee suburb.

Wisconsin, along with Michigan and Ohio are crucial US Rust Belt battleground states in the November election.

"The path to the White House goes through Wisconsin. And to win in Wisconsin, we are counting on you, right here in Milwaukee," Harris said in the 17-minute speech. "Do we want to live in a country of freedom, compassion and rule of law, or a country of chaos, fear and hate?" she said. "We believe in the sacred freedom to vote. We believe that every person in our nation should have the freedom to live safe from the terror of gun violence … and we trust women to make decisions about their own bodies."

Of her time as a prosecutor in California, Harris said she "took on perpetrators of all kinds: predators who abused women; fraudsters who ripped off consumers; cheaters who broke the rules for their own gain. So hear me when I say, I know Donald Trump's type," in an apparent reference to some of the former president's legal issues.

Harris has previously served as the San Francisco district attorney, the California attorney general and a US senator from the state.

She has faced some controversy for her stance on marijuana. During Harris' tenure as district attorney in San Francisco from 2004 to 2011, more than 1,900 people were convicted for marijuana offenses, Forbes reported.

She opposed a California ballot initiative in 2010 that would legalize cannabis, although she did favor its medical use. In 2015, she favored the lifting of a federal ban on medical marijuana.

In a call with reporters on Tuesday, Trump criticized Harris' record on immigration since she was tasked by Biden with looking into the root causes of the migration surge.

"Kamala Harris was appointed border czar, as you know, in March 2021, and since that time, millions and millions of illegal aliens have invaded our country, and countless Americans have been killed by migrant crime because of her willful demolition of American borders and laws," Trump said on the call.

A July 22 YouGov poll showed Trump had a 15 percent lead on Harris on the issue of immigration.

Recent polls on voter preference overall are mixed.

Harris led Trump 44 percent to 42 percent among registered voters in a national Reuters/Ipsos poll, conducted on Monday and Tuesday.

A recent YouGov poll showed Trump ahead 44 percent to 39 percent, among registered voters. A Yahoo News poll had each candidate with 46 percent, in a contest that has five candidates.

Trump said Tuesday that he would like to debate Harris "more than once" but did not commit to appearing at the next scheduled debate in September on ABC.

Trump told reporters that he was "not thrilled at ABC" and may want another network, such as Fox, to air the debate. He said he'd only agreed to debate Biden twice — during the June 27 debate that led to the president bowing out of the race, and then in September.

But Trump said he still wants to debate Harris.

"I think debating's important for a presidential race," he said. "You sort of have an obligation to debate."

Agencies contributed to this story.