Career
He served first as a Democrat in the elections of 1972, 1975, 1979, and 1983 and then as a Republican in the contest held in 1987. His tenure ended in 1992, and he was succeeded by the Republican Jay Dardenne, the current Lieutenant Governor of Louisiana. His legislative service corresponded with the first three administrations of Governor Edwin Edwards and the intervening years of Governors David C. Treen and Buddy Roemer.
Prior to his Senate service, Osterberger was from 1969 to 1972 the President Pro Tempore of the Baton Rouge Metro government.
In 1975, in his first reelection to the state Senate, Osterberger polled nearly two-thirds of the votes cast in the first ever nonpartisan blanket primary held in Louisiana, when he was challenged by the then Democrat, later Republican convert, David Duke, a former official with the Ku Klux Klan who then resided in Baton Rouge. In 1983, Osterberger in his last race as a Democrat defeated the Republican "Rocky" Powell, 29,816 (738 percent) to 10,607 (262 percent).In Osterberger"s last election to the Senate, as a Republican in 1987, he polled 37,172 votes (808 percent) to 8,845 (192 percent) for A. T. "Apple" Sanders, Junior., a Democrat who served in the Louisiana House of Representatives from 1956 to 1964.