tonight: margaret warner gets the latest on one of the deadliest prison fires in a century from nicholas casey of the "wall street journal." >> ifill: then, we turn to the g.o.p. presidential race, where former pennsylvania senator rick santorum is breaking into the lead. >> brown: we get two views on the safety and wisdom of building the nation's first new nuclear reactors in more than three decades. >> ifill: from tunisia, we have a report on the economic and political struggles of a fledgling democracy one year after the revolution that sparked the arab spring. >> what happened is it gave people the belief that someone is not as only nip at the present time as they thought they are. libya has a real shot as building a real democratic society. >> brown: and ray suarez examines the efforts to resolve a critical drug shortage, involving a treatment for childhood leukemia. >> ifill: that's all ahead on tonight's "newshour." major funding for the pbs newshour has been provided by: >> and by the bill and melinda gates foundation. dedicated to the idea that all people deserve the chance to live a