Simplify the following text for a Grade 5 native English-speaking person.
Original: Byrd led the Democratic caucus as Senate Majority Leader from 1977 to 1981 and 1987 to 1989 , and as Senate Minority Leader from 1981 to 1987 .
Simplified: He served as majority leader from 1977 to 1981 and again from 1987 to 1989 . He was also minority leader from 1981 to 1987 .