Complex sentence: He held various posts in the Social Democratic Party organization from 1967 to 1979, but he first came into the political limelight when he was secretary to the then Prime Minister Mauno Koivisto from 1979 to 1982.
Split into simpler sentences: He held various posts in the Social Democratic Party organization from 1967 to 1979. Lipponen first came into the political limelight when he was secretary to the then Prime Minister Mauno Koivisto from 1979 to 1982.