MANAGUA, Nicaragua—The government of Nicaraguan President Daniel Ortega arrested five opposition leaders during a major weekend round up, in what appears to be widespread detentions of anyone who might challenge his rule. The four arrests Sunday and one Saturday suggest Ortega has moved beyond arresting potential rival candidates in the Nov. 7 elections, and has begun arresting any prominent member of the opposition. The arrests bring to 12 the number of opponents detained since June 2. “It’s not just potential candidates any more, it’s political leaders,” former general and Sandinista dissident Hugo Torres told The Associated Press before he himself was arrested Sunday. “This is not a transition to dictatorship, it is a dictatorship in every way.” On Sunday, police also arrested prominent ex-Sandinista dissident Dora María Téllez, another opposition leader, Ana Margarita Vijil, and Suyen Barahona, leader of the political movement Unamos. Tellez’s arrest is a major step: she …