Complex sentence: Rusher was an early mentor of Young Americans for Freedom, founded with his assistance in 1960, and also helped to found the Conservative Party of New York in 1961 and the American Conservative Union in 1964-65.
Split into simpler sentences: Rusher was an early mentor of Young Americans for Freedom, founded with his assistance in 1960. He helped to found the Conservative Party of New York in 1961 and the American Conservative Union in 1964-65.