Former Goldman Sachs CEO Lloyd Blankfein fired back at Sen. Elizabeth Warren (D-MA) on Twitter Thursday morning with a provocative joke that clearly served to remind voters about her Native American heritage controversy. “Vilification of people as a member of a group may be good for her campaign, not the country,” he wrote, adding, “Maybe tribalism is just in her DNA.”

The billionaire businessman was responding to a new Warren 2020 campaign ad that features clips of him and several other billionaire businessmen attacking her policies. The ad is currently scheduled to run on CNBC. “She probably thinks more of cataclysmic change to the economic system as opposed to tinkering,” Blankfein says in the ad before the words “Earned $70 million during the financial crash” appear over his face.