Lester Holt, the anchor and managing editor of “NBC Nightly News” for a decade, announced Monday that he is stepping down from the long-running broadcast at the beginning of the summer. Holt will continue to be a fixture at the network with a full-time role at “Dateline,

The longtime newscaster said he would leave the daily news show at the “start of summer.” NBC did not immediately name a successor.

Holt has been a calming presence at NBC News, where his unflappable and low-key demeanor helped the news division move forward after a period of tumult. He took over “Nightly” duties after his predecessor, Brian Williams, was removed following scrutiny of claims the latter made about the details of a reporting trip to Iraq.