Complex sentence: The movements reemerged in 1951 in both the Republican and Democratic parties, as Eisenhower had not yet announced any political party affiliation and believed that he needed to remain nonpartisan, citing Army regulation 600-10.18.i forbidding partisan political activity by serving officers.
Split into simpler sentences: The movements reemerged in 1951 in both the Republican and Democratic parties, as Eisenhower had not yet announced any political party affiliation. Eisenhower believed he needed to remain nonpartisan, citing Army regulation 600-10.18.i forbidding partisan political activity by serving officers.