BOSTON — NPR is ending the 21-year-old call-in radio show “Talk of the Nation” and will encourage local stations to replace it with an expanded version of “Here and Now,” an afternoon news broadcast that is produced here, the organization announced on Friday.

The plan is the product of discussions that began more than two years ago between NPR and some of its biggest member stations. For the middle of the afternoon the stations wanted a magazine-style news show along the lines of “Morning Edition” and “All Things Considered,” the two bookends of most stations’ weekday schedules.

“Here and Now” fits that description. The program, produced by the Boston University station WBUR, started locally in 1997 and began to expand nationally in 2001. Until now, it has been distributed by a rival programmer, Public Radio International, but starting this summer, it will be distributed by NPR instead.

NPR will work with WBUR to turn the one-hour “Here and Now” into a two-hour show, with contributions from NPR’s news staff and other local stations. A co-host, Jeremy Hobson, will join the program’s current host, Robin Young.