Willie Nelson, Bonnie Raitt, Dave Matthews, Nathaniel Rateliff and other musical luminaries will come together Sept. 30 to shine a light on former Colorado Gov. John Hickenlooper’s campaign for the U.S. Senate. “Hick-a-Palooza,” as the virtual event is called, will feature performances from a string of acts that the Democratic former governor and Denver mayor booked to raise money for his fight against incumbent Republican Sen.