CNN's TV ratings have struggled to catch up to Fox News and MSNBC. (joevare/Creative Commons)

Walton, who has spent his entire 30-year career at CNN, presided over a network that has been losing ground to rivals Fox News and MSNBC. Prime-time viewership at CNN, which is owned by Time Warner Inc., dropped 8 percent to 627,000 through mid-May, compared with a year earlier. News Corp.’s Fox News drew an average prime-time audience of 1.85 million in the same period.

“CNN needs new thinking,” Walton said in a memo to staff. “That starts with a new leader who brings a different perspective, different experiences and a new plan, one who will build on our great foundation and will commit to seeing it through.”

While Fox and MSNBC feature partisan hosts in their prime-time programs, Walton has balked at going that route, believing that CNN’s worldwide reputation would be tarnished if it broke from its mission of being a nonpartisan news source, according to the Associated Press.

Walton will remain with CNN until the end of the year, while the network begins its search for a replacement.

Read the full story at Bloomberg News or the Associated Press. For more on Neon Tommy’s coverage of CNN, click here.

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