Has the countdown begun for the end of “Countdown with Keith Olbermann?” With his ratings in free-fall, and his hateful histrionics reaching new highs, even Olbermann’s former supporters on the left are tuning out. Bloggers at the Los Angeles Times and National Public Radio noted the uberdork’s 44 percent drop in listeners ages 25-54 from January 2009 to last month. “Olbermann’s showboat is sinking,” one LA Times blogger noted. “Listing in you-know-which direction.” Jon Stewart ridiculed him on “The Daily Show” for calling Massachusetts Senator-elect Scott Brown a “racist.” “There are creeping indications that the world may not have quite as much need of — or patience for — Olbermann and his shtick as it once did,” Jeff Bercovici wrote on DailyFinance.com. Olbermann struck back at Bercovici, naming him as one of the “Worst People in the World” and mischaracterizing the Web site as “right-wing.”