George Stephanopoulos is returning to Sunday mornings at ABC News, replacing Christiane Amanpour as host of the political talk show "This Week."

ABC said Tuesday that Stephanopoulos, who returns Jan. 8, will remain as host of "Good Morning America," although likely on a four-day schedule.

Amanpour, meanwhile, enters an unusual job-sharing role where she will become ABC's global affairs anchor, contributing to prime-time shows on world news, while also being host of a daily show on CNN International.

"This role is groundbreaking, bold and very different," Amanpour said. "I am thrilled and honored."

Critics wondered from the start whether the Iranian-born Amanpour, a veteran foreign correspondent for CNN, was a good fit for a panel show dominated by American politics. It hasn't budged from third place behind NBC's "Meet the Press" and a resurgent "Face the Nation" on CBS, with the ABC show down 1 percent in ratings from last year.

Amanpour's reporting connections in the Middle East served ABC News particularly well during the Arab spring, and she scored an exclusive interview with then-Egyptian President Hosni Mubarak in February.

But the dawning of an American election year seemed to serve her competitors, old Washington hands Bob Schieffer at CBS and David Gregory at NBC, better.

The Sunday morning show was much stronger in the ratings behind Stephanopoulos, who was host from 2002 to 2010. ABC moved him to New York and "Good Morning America," which has done well in the ratings by teaming him with Robin Roberts.

Amanpour said she was looking forward to getting back out to do more international reporting and speaking to a worldwide audience on CNN, where she worked for more than two decades.

"Christiane Amanpour has been synonymous with international repo8rting and with CNN for many years," said Jim Walton, president of CNN Worldwide. "We could not be happier that through this unique arrangement with ABC News her experience and global perspective are returning to a nightly news broadcast for our international audience."

Amanpour will be making occasional appearances on CNN's U.S. channel, spokeswoman Christa Robinson said.

Amanpour replaced Stephanopoulos at "This Week" starting in August 2010.

Gregory's "Meet the Press" is averaging 2.92 million viewers this season on Sundays, but that's down 5 percent from last year. Schieffer's "Face the Nation," at 2.86 million viewers, is up 6 percent, the Nielsen Co. said. "This Week" is averaging 2.26 million viewers this season.

CBS announced Sunday that "Face the Nation" would expand to one hour next spring from its current half-hour format. Both "Meet the Press" and "This Week" air for one hour.