NEW YORK (AP) -- CNN chief Jim Walton said Friday he is quitting, saying the company needs new leadership at a time its flagship U.S. network is suffering through some of its poorest ratings ever.
Walton built the company into a profitable international news organization in his 10 years as president of CNN Worldwide, and said it is on track for record profits this year. But the U.S. network is the most visible part of the business and is now entrenched in third place behind rivals Fox News Channel and MSNBC in prime time.
He announced the decision in an email to staff members on Friday. He said he'll continue working until the end of the year during the company's search for a successor.
Walton said he's been talking to his boss, Turner Broadcasting Chairman Phil Kent, about leaving since the first few months of the year. CNN is owned by Time Warner.
"There's always pressure," he said. "I've been doing this a long time and CNN has had its ups and downs, like all companies have had ups and downs. I feel really strongly about a number of parts of this company. We're having a really strong year internationally and in mobile. It's clear there's a lot of spotlight on CNN's U.S. performance and it's reasonable that there is that spotlight."
CNN's U.S. network had its worst-ever ratings for a second quarter, down 40 percent for some of its prime-time shows. The decline was particularly notable in May, when CNN faced tough competition from broadcast networks during a slow news period and its ratings were compared to a year earlier, in the aftermath of the Osama bin Laden killing.
It hasn't improved appreciably since then, with veteran newsman Wolf Blitzer often losing in the ratings to broadcast novice Al Sharpton on MSNBC. Piers Morgan's show has been a bright spot this month.
The network was also embarrassed by initially reporting incorrectly the U.S. Supreme Court's decision on President Obama's health care law, then taking longer to correct itself than Fox, which made a similar error.
CNN's ratings traditionally fluctuate based on the intensity of the news. Fox and MSNBC have insulated themselves from that problem somewhat through its partisan prime-time hosts. Walton has resisted this approach, believing CNN's strength lies in being a nonpartisan news source and the company's reputation would be damaged worldwide if the U.S. network changed.
Walton said he doesn't expect that to change after he leaves.
"We kind of know who we are and our corporate colleagues know who we are and there has always been great support internally that we're going to be a news organization," he said.
At CNN, "we want to be accurate above all else, we want to be timely — first if possible — we want to actually go to where the news is, not just subscribe to some agency's news feed and talk about it. We want to report the news from multiple sides, all sides, and without bias."
Walton, 54, began working at CNN in 1981 shortly after it started. His first job involved ripping paper scripts off wire machines and operating the TelePrompter for news anchors.
Jeff Bewkes, Time Warner chairman and CEO, said Walton took over an underperforming company in 2003 and tripled earnings, delivering an annual growth of 15 percent. Roughly half of the company's earnings come through subscription fees from cable and satellite companies, and they have been growing steadily worldwide.
"Jim has been instrumental in growing the business into the financial powerhouse it has become, while establishing the brand as the worldwide leader for television news," Bewkes said. "I respect him personally and professionally and support the decision he and Phil Kent have reached."
Kent said Walton has a track record of great judgment when it matters most. He "challenged the organization to think bigger, reach further, do better," he said.
"I think this company needs some new thinking," Walton said. "I've been doing this job I'm in now for 10 years and I'm ready for a change."