Democratic presidential candidate Senator Elizabeth Warren is firing right back at the billionaires who've been criticizing her tax proposals, particularly her signature "wealth tax" on the richest Americans, by airing an ad this week on the financial network CNBC. The ad, called, "Elizabeth Warren Stands Up to Billionaires," even names names, singling out four billionaires in particular -- investor Leon Cooperman, former TD Ameritrade CEO Joe Ricketts, former Goldman Sachs CEO Lloyd Blankfein and Silicon Valley investor Peter Thiel. Cooperman said in a CNBC interview in response to Warren's ad, "In my opinion, she represents the worst in politicians as she's trying to demonize wealthy people because there are more poor people than wealthy people. . . . She's disgraceful. She doesn't know what the f*** she's tweeting. I gave away more in the year that she has in her whole f***ing lifetime." Among the wealthy upset about Warren's proposals are Democratic donors, who've been signaling to party leaders that they'll either sit out the 2020 election or even support President Trump's re-election if she's the nominee.