Former Vice President Joe Biden hit three private fundraisers in Chicago on Thursday, prompting some criticism from presidential rival Bernie Sanders over a statement made by one of his hosts — billionaire casino and real estate mogul Neil Bluhm — and highlighting what many see as a major divide in the Democratic party.

At the first fundraiser, Biden stopped by a luncheon at Bluhm’s sprawling downtown residence near the Mag Mile. Biden was introduced by Bluhm, who told his high-profile guests that both presidential candidates Elizabeth Warren and Sanders “don’t represent the Democratic Party” that Bluhm supports. Bluhm said Biden “has the best chance of defeating Trump.”

That prompted a response from Sanders’ campaign: “Mr Bluhm is right — the Democratic Party I represent is the party of the working class, not billionaires. That’s why we’re going to win,” the Sanders campaign said in a statement to CNN.

Sanders statement hit as Biden — considered the most centrist of the Democratic frontrunners — visited the homes of wealthy donors in Chicago. And it came as Sanders — vying with Warren for the party’s more progressive wing — announced his campaign had received donations from more than one million individual donors.

But Biden focused his stump speeches on the general need for the nation to “pick our heads up.”

“I’m so tired of everybody walking around with their heads down saying, ‘What’s the United States going to do?’ For God’s sake, this is the United States of America. We have not only the strongest military in the world but we have the most respect in the world. We’re in a situation where we have more great research universities in America than every other country combined,” Biden said at the first event. “It’s time we pick our heads up and prove who in God’s name we are. This is the Unites States of America.”

And a day before attending a climate change town hall in Iowa, Biden said the first thing he’d do as president is have the U.S. rejoin the Paris climate accord.

“Somebody has to rally those nations to say, we are damaging our reputation so badly,” Biden said.

Of global warming, Biden said it should be looked at “not just as an existential threat but as the enormous opportunity to create millions of really good paying jobs.”

The second of three Chicago fundraisers was an evening reception at the Streeterville residence of philanthropists Sharyl and Mike Mackey, and co-hosted by Sheila Nix, former chief of staff to Dr. Jill Biden, as well as Perkins Coie partner James Coughlan.

In introducing Biden, Nix said the most important issue facing the nation is restoring democracy.

“I really truly believe there’s only one person that can save our country from where we are right now, and that’s Vice President Biden.”

Biden spoke for about 24 minutes atop a glass staircase, and he invoked Barack Obama nearly immediately: “In his hometown, I just want to thank him for all of you.”

Apparently referring to some of his Democratic rivals, Biden said there’s a “newfound sense, ‘maybe we should pick on Barack a bit.’ And by the way it’s just absolutely stupid.”

Biden echoed his calls to “restore the soul” of the country and rebuild the middle class.

“We’re unique in that we cherry pick the best of every culture in the world,” Biden said. “It takes resilience, optimism, determination. And what worries me most is that, I’m worried that we are not providing the kind of opportunity for people here who have been here a long, long time — the poor and the working poor and the middle class. It doesn’t matter where they are.”

Guests at the second fundraiser included former U.S. Ambassador Carol Moseley Braun, former Illinois Gov. Pat Quinn; Chicago Ald. Jason Irvin (28th) and his wife, Chicago City Treasurer Melissa Conyears-Irvin; Cook County Sheriff Tom Dart and former State Rep. Lou Lang.

The final Chicago fundraiser of the day was a dessert reception hosted by real estate moguls Emily and Thad Wong in their Lincoln Park home. In introducing Biden, Thad Wong said his father admired the former vice president for many reasons, including his resilience after experiencing tragedy.

”When he dug in, many of us would have given up,” he said.

The last stop invoked more personal accounts from Biden, who spoke of the loss of his son Beau, whom he called his “soul.”

”I think about the real incredible, incredible number of people I know who get up every single morning, who have been through more than I have, and put one foot in front of the other. One of the jobs I had was to keep going. Keep going. And folks, that’s one of the reasons I’m running.” Biden said.

And singling out claims that he’s “naive,” Biden spoke of conversations he’s had with people who ask why he’s stayed in politics so long and whether it’s time to pass the torch.

”I thought hanging around a lot would mean you at least picked up that you weren’t naive,” Biden said. “Here’s what I’m not naive about. Unless we figure out how to unite the country, none of this works. None of this works.”