Complex sentence: O'Brien was appointed in 1960 by Sen. Kennedy to serve nationally as the director of his presidential campaign.His election planning in key primary states such as Wisconsin and West Virginia convinced many in the party that Sen. Kennedy's Catholicism wasn't a problem.
Split into simpler sentences: O'Brien was appointed in 1960 by Sen. Kennedy to serve nationally as the director of his presidential campaign. O'Brien's election planning in key primary states such as Wisconsin and West Virginia convinced many in the party that Sen. Kennedy's Catholicism wasn't a problem.