Dozens of artists signed a letter asking the US Senate to "take action on background checks" for gun purchases, in a campaign organized by Billboard. The esteemed signees: Christina Aguilera, Tori Amos, Sara Barielles, Aaron Bay-Schuck, Tony Bennett, Selim Bouab, Rob Bourdon, Scooter Braun, Cortez Bryant, Michael Bublé, Vanessa Carlton, Joseph Carozza, Steve Cooper, Tom Corson, Lee Daniels, Ellen DeGeneres, Brad Delson, Diplo, Mike Easterlin, John Esposito, Melissa Etheridge, Fletcher, Luis Fonsi, Becky G, Kevin Gore, Julie Greenwald, Josh Groban, Horacio Gutierrez, Joe Hahn, Halsey, Billy Joel, Craig Kallman, Alicia Keys, Kid Cudi, Carole King, Elle King, Adam Lambert, Cyndi Lauper, Kevin Liles, Dre London, Jennifer Lopez, Macklemore, Zayn Malik, Carianne Marshall, Ricky Martin, Paul McCartney, Julia Michaels, Guy Moot, Jason Mraz, Gregg Nadel, Yoko Ono, Mark Pinkus, Gregory Porter, Prince Royce, Bonnie Raitt, Dawn Richard, RMR, Paul Robinson, Maggie Rogers, Kelly Rowland, Mike Shinoda, Sia, Matt Signore, Britney Spears, Rob Stevenson, Sting, Barbra Streisand, Justin Tranter, Sir Trilli, Sharon Van Etten, Aimie Vaughn-Fruehe, Eddie Vedder, Andrew Watt.