MSNBC tried a bold experiment this year by putting two politically incendiary hosts, Keith Olbermann and Chris Matthews, in the anchor chair to lead the cable news channel’s coverage of the election.

That experiment appears to be over.

After months of accusations of political bias and simmering animosity between MSNBC and its parent network NBC, the channel decided over the weekend that the NBC News correspondent and MSNBC host David Gregory would anchor news coverage of the coming debates and election night. Mr. Olbermann and Mr. Matthews will remain as analysts during the coverage.

The change — which comes in the home stretch of the long election cycle — is a direct result of tensions associated with the channel’s perceived shift to the political left.

“The most disappointing shift is to see the partisan attitude move from prime time into what’s supposed to be straight news programming,” said Davidson Goldin, formerly the editorial director of MSNBC and a co-founder of the reputation management firm DolceGoldin.