Booker, Gillibrand and Harris are all rising stars in the party, but lack the name identification of Warren and Sanders.

The question and answer session was the most revealing part of the summit. Some senators used the questions posed by attendees to make subtle moves meant to endear themselves to progressives.

The 47-year-old Booker, who has previously drawn criticism from progressives for donations he received from pharmaceutical companies and big businesses, sought to make clear that he’d protect the little guy.

He blasted hedge funds and corporations who practice “perverse capitalism” that prioritizes dividends and executive bonuses over workers. He specifically singled out Bain Capital, a shift from the 2012 presidential campaign when he referred to Democratic attacks on the private equity firm — which was co-founded by then-Republican presidential nominee Mitt Romney Willard (Mitt) Mitt RomneyBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power The Memo: Trump's strengths complicate election picture MORE — as “nauseating.”

“I support a lot of legislation and ideas to end these kind of toxic practices, to put workers back in the center of the company’s focus,” Booker said.

Gillibrand, 51, also took the opportunity to take a step further to the left in her economic platform.

When pressed by an organizer from an Indivisible chapter if she supports the financial transaction tax, Gillibrand said she does, attracting applause. Sanders sponsored a bill in 2017 that would impose taxes on specific trading transactions. Supporters of this tax believe it would discourage stock market speculation.

“I think income inequality is the greatest risk we have to our democracy right now,” Gillibrand added.

Meanwhile, Booker, Harris and Gillibrand sought to differentiate themselves from the pack and prove their progressive bona fides.