Norah O'Donnell leaving as anchor of CBS evening newscast after election

Norah O'Donnell is leaving as anchor of the “ CBS Evening News” after the presidential election, she announced on Tuesday.

O'Donnell has been top anchor of the newscast for five years and prior to that anchored the network's morning show. She told CBS News colleagues in an email that it's time to do something different after time spent “tied to a daily broadcast and the rigors of a relentless news cycle.”

She said she is staying with CBS News to contribute interviews and other stories, but in a role not fully defined. CBS says it is committed to the broadcast continuing, but gave no indication of who will be replacing her.

The “CBS Evening News,” the perch from which Walter Cronkite and Dan Rather held forth for many years, generally runs third in the network ratings behind ABC 's “World News Tonight” with David Muir and the “NBC Nightly News” with Lester Holt .