 These sources said Greenberg has sent several memos over the past two weeks since the president's devastating debate performance, analyzing internal polling, he asserts, shows the president's position continues to deteriorate because Americans overwhelmingly do not see him as up to serving four more years. Greenberg has been a leading Democratic pollster for decades, and his work includes advising Bill Clinton's two winning presidential campaigns. He declined to comment. Now, I will tell you, a listener in Tulsa.