>> Photos: Johnny Isakson through the years
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1974: Runs unsuccessfully for the state House.
1976: Wins election to the state House. He serves seven terms in the chamber.
1983: Republicans elect Isakson as the state House minority leader. At the time, there are only 24 Republican members in the state House. Isakson holds the minority leader title until 1990.
1990: Runs unsuccessfully for governor.
1993: Enters the state Senate and serves there until 1996.
1996: Runs for the U.S. Senate but loses in the primary.
1997: Gov. Zell Miller names Isakson chairman of the state Board of Education.
1999: Wins a special election to fill the seat Newt Gingrich vacated when he resigned from Congress.
2004: Wins election to the U.S. Senate.
2010: Wins re-election to the U.S. Senate.
2015: Takes the reins of the U.S. Senate's Veterans Affairs and Ethics committees. (He's the only senator currently holding two chairmanships.) In June, he also reveals that he has been diagnosed with Parkinson's disease.
2016: Wins re-election to the U.S. Senate.
July: Suffers four broken ribs and other injuries in a fall.
Wednesday: Reveals that he underwent kidney surgery and that he will be resigning from office on Dec. 31.