CNN on Wednesday canceled Eliot Spitzer’s 8 p.m. political talk show, “In the Arena,” after only nine months amid a broader shake-up that shifts Anderson Cooper’s 10 p.m. nightly newscast into Mr. Spitzer’s time slot.

Art Streiber/CNN

The cable news channel also said that Erin Burnett, a new hire from CNBC, would take over the 7 p.m. time slot on weekdays, replacing John King, who will move to 6 p.m.

The changes are intended to stabilize the sagging television ratings for CNN, which have been a source of frustration for the channel’s parent company, Time Warner. “We think it creates better flow from show to show, and we think that will improve the overall performance across the evening,” Ken Jautz, who was put in charge of CNN/U.S. last fall, said in an interview.

The only prime-time show unaffected by Wednesday’s announcements is “Piers Morgan Tonight,” the 9 p.m. interview show that was introduced six months ago.

The changes make “Anderson Cooper 360,” already the flagship program on CNN, into an even more important part of the channel’s programming mix. Once it is moved to 8 p.m., the program will be rebroadcast at 10 p.m.

Mr. Jautz said that 8 p.m. had come to be “emblematic of what a news network stands for,” and that Mr. Cooper’s program “embodies CNN’s strength and its uniqueness.” As a straightforward newscast, it stands in contrast to the conservative-leaning 8 p.m. show on Fox News and the liberal-leaning one on MSNBC.

The change at 8 p.m. will take effect Aug. 8. Then, in late September, “The Situation Room With Wolf Blitzer,” which currently runs from 5 to 7 p.m., will move to 4 to 6 p.m. Mr. King’s show will then move to 6, and Ms. Burnett’s still-untitled news show will be introduced at 7 p.m., with a rebroadcast at 11 p.m.

But the fallout was already evident on the air on Wednesday night, as Mr. Spitzer signed off his show right away. Mr. Jautz said Wednesday afternoon that CNN was in discussions with Mr. Spitzer about an “alternative role,” but a representative for Mr. Spitzer said that his work for CNN was finished, and that he would soon be allowed to have talks with other networks about jobs.

For Mr. Spitzer, who has tried to rehabilitate his public image since resigning the New York governorship in disgrace three years ago, the cancellation was a setback that caused a new round of ridicule by comics and online commenters.

Mr. Spitzer was hired last summer by Mr. Jautz’s predecessor, Jonathan Klein, who was dismissed weeks before the resulting show, “Parker Spitzer,” had its premiere. The show was plagued by poor ratings, prompting the exit of his co-host, Kathleen Parker, in February, and its renaming.

He signed off on Wednesday by putting on his glasses and reading a 1910 speech by Theodore Roosevelt that inspired his show’s title. He quoted, “It is not the critic who counts; not the man who points out how the strong man stumbles, or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood, who strives valiantly; who errs; who comes short again and again.”

Mr. Spitzer concluded the quote, “Because there is no effort without error and shortcoming; who, at the worst, if he fails, at least fails while daring greatly; so that his place shall never be with those cold and timid souls who neither know victory nor defeat.”