CNN announced Wednesday that it will cancel John King’s evening news show. JK USA, which has aired in the 6 p.m. time slot since 2010, was consistently CNN’s least-watched evening show, a sad spot to occupy on the network that has recently been experiencing a particularly bad ratings stretch. The empty 6 p.m. slot will be filled by Wolf Blitzer’s “Situation Room,” which will now be expanded to three hours in length. King will remain with the network as the lead national correspondent. He has already covered seven presidential campaigns, four of them with CNN.