Democratic vice presidential candidate Tim Walz told donors at a Denver fundraiser on Wednesday afternoon that he shares a “politics of kindness” with his running mate, Vice President Kamala Harris, but the Minnesota governor warned against mistaking kindness for weakness.

Comparing former President Donald Trump, their Republican rival, to the “fraudsters” and “predators” once prosecuted by Harris, Walz contrasted the presidential nominees’ backgrounds.

“She goes after the folks who cheat the system, try and make it harder for others. She knows who that is,” Walz said. “That’s what she did. That’s the job she did.”

Walz spoke to roughly 150 supporters in the backyard of the historic Phipps Mansion, owned by Democratic megadonor and LGBTQ activist Tim Gill and his husband, Scott Miller, the U.S. ambassador to Switzerland and Liechtenstein.

Gill said the fundraiser — for the Harris Victory Fund, with tickets priced from $1,000 to $50,000 — brought in $3 million, according to a pool report.

“This week has been interesting,” said Walz, who was tapped by Harris to be her running mate on Aug. 6, just over two weeks after President Joe Biden upended the race for the White House by withdrawing and endorsing Harris.

“That’s a Minnesota word, ‘interesting’ — you Minnesotans know, it has multiple meanings,” Walz added, drawing laughter from the crowd.

Walz said that after the Harris campaign whisked him off to a rally in Philadelphia and told him, “‘Here, you’ve got 45 minutes to read this speech off the teleprompter,’” he had to tell them something: “‘Perhaps I neglected to tell you, I’ve never used a teleprompter in my life.’”

The Colorado event was the second stop on Walz’s three-day, five-state cross-country swing, including speeches and fundraisers in California, Massachusetts, Rhode Island and New York. The series of solo appearances by Walz followed the Democratic ticket’s whirlwind tour of swing states last week, with massive rallies in Pennsylvania, Georgia, Wisconsin, Michigan, Arizona and Nevada.

Trump attended a private fundraiser in Aspen on Saturday, part of a Western-states tour he said raised $28 million for his campaign.

Gov. Jared Polis, who served in the U.S. House with Walz before both won election as governors in 2018, said in remarks introducing Walz that the two had common achievements in their respective states, including providing school lunches without charge and protecting abortion rights.

“That’s what Tim Walz has been all about in Minnesota,” Polis said. “That’s what Kamala Harris and Tim Walz are going to bring to our country, so that states like Colorado, Minnesota and so many others have a partner in the White House, rather than an adversary in the White House.”

Polis added that he’d told Walz “not to invest any money here,” assuring him that the Harris-Walz ticket would not only carry Colorado but bolster the party’s down-ballot races.

The Democratic nominee has won Colorado’s electoral votes in every presidential election since 2008, including Biden’s 13.5-point win over Trump four years ago. Election forecasters rate the state as solidly in the Democrats’ corner this fall, in part because the party’s candidates have swept every statewide race since 2018.

Colorado’s Republican Party didn’t respond to a request for comment on Walz’s visit to the state.

Other prominent Democrats in attendance at the fundraiser included U.S. Rep. Joe Neguse, the assistant House Democratic leader; former U.S. Reps. Ed Perlmutter and John Salazar; Colorado Secretary of State Jena Griswold; former Denver Mayor Wellington Webb; Colorado Democratic Party Chairman Shad Murib; and Polis chief of staff Alec Garnett, a former speaker of the Colorado House of Representatives.

When Walz described what he characterized as the humbling experience of listening to Harris speak before enormous crowds, Polis interjected: “Are you saying they’re not all AI?”

Polis’ crack, which prompted laughter from the crowd, was referencing Trump’s claim this week that the Harris campaign had used artificial intelligence to depict larger crowds than actually showed up for a rally at an airport in Michigan.

“I assure you, in Detroit, that wasn’t AI, and I’ll also assure you that every one of the ballots they’re going to cast will not be AI,” Walz responded, drawing cheers.

Maintaining that the United States has a duty to lead on critical issues, Walz touched briefly on several topics without going into specifics, including calling for “common-sense gun legislation” in respond to school shootings.

“We have to address climate change and we need to be leaders,” Walz said. “We need to address hunger and poverty. We need to address wars and conflicts, those are things.”

Said Walz: “The United States is more than just a country. We’re an ideal, the ideal of so many of our — the beliefs around the world that something can be better. We can live up to those ideals.”

With just 83 days remaining until votes are counted, Walz told supporters to push themselves until Election Day, adding what has become one of the candidate’s trademark phrases: “Sleep when you’re dead.”