Dennis Moore won his first bid for public office in 1976, when he defeated Republican incumbent Margaret Jordan by just 1,468 votes out of 106,290 cast to become Johnson County district attorney. He won re-election without opposition in 1980, and won in 1984 with 61 percent of the vote.
He did not seek re-election in 1988 after losing the 1986 race for attorney general to incumbent Republican Bob Stephan, who won the third of his four terms as attorney general with 53 percent of the vote.
Moore returned to the political arena in 1993 when he won election to the Johnson County Community College Board of Trustees. He was re-elected in 1997.
In 1998, Moore was elected to the U.S. House, unseating Republican Rep. Vince Snowbarger with 52 percent of the vote. In 2000, he was re-elected with 50 percent of the vote in a hard-fought campaign against conservative Republican Phill Kline.
A GOP moderate, newcomer Adam Taff, won the nomination to challenge Moore in 2002, but Moore won, 50 percent to 47 percent.