And it’ll be the Center for American Progress’s biggest move yet to establish itself as both the nexus of the Democratic Party’s future — and a player trying to shape what that future will be.

They’re roughly modeling the event on CPAC, the American Conservative Union’s annual gathering that’s become a prime stop for Republican leaders, and which notably gave Donald Trump his first major political platform as he was entering the fray.

“So much of our time right now is engaged, and rightfully so, in fighting Trump. On any given day, he issues one affront to progressive values after another,” said CAP president Neera Tanden. “It’s obviously critical that we provide a positive alternative of how we’re going to address the country’s challenges.”

Sens. Elizabeth Warren (D-Mass.), Cory Booker (D-N.J.), Kamala Harris (D-Calif.), Chris Murphy (D-Conn.) and Kirsten Gillibrand (D-N.Y.), Montana Gov. Steve Bullock and Los Angeles Mayor Eric Garcetti are all confirmed to attend, and more are expected to be added to the event, scheduled for May 16.