Complex sentence: This convention was founded in 1964, by then-state representative Bob Packwood as a forum for all Republicans statewide, but in the 1990s was dominated by members of the conservative branch of the party.
Split into simpler sentences: This convention was founded in 1964 by then-state representative Bob Packwood as a forum for all Republicans statewide. In the 1990s it became dominated by members of the conservative branch of the party.