Barack Obama served three terms in the Illinois Senate from 1997 to 2004, when he was elected to the United States Senate. During this part of his career, Obama continued teaching constitutional law part time at the University of Chicago Law School as he had done as a Lecturer from 1992 to 1996, and as a Senior Lecturer from 1996 to 2004.
In 1994, Senator Alice Palmer decided to run for the United States House of Representatives, leaving the Senate's 13th district seat open. When filing opened in 1995 for her seat, Obama entered the race. Eventually, his challengers were disqualified and he won the Democratic primary unopposed in 1996. He won re-election in 1998 and 2002. During his Senate tenure, Obama was involved with a wide range of legislation.