Alan Keyes challenged ran for the U.S. Senate in Maryland in 1988 and was soundly defeated by Democratic incumbent Sen. Paul Sarbanes, receiving just 38.2 percent of the vote. Keyes ran as a stand in for the winner of Maryland's Republican primary, who withdrew midway through the campaign.
In 1992, Keyes took on Sen. Barbara Mikulski, D-Md., and ended up with just 29 percent of the vote.
Undiscouraged by two Senate defeats, Keyes sought the Republican presidential nomination in 1996 and 2000. He failed to win a primary in either race.
The Illinois Republican Party chose Keyes to run for the U.S. Senate in 2004 after nominee Jack Ryan withdrew amid controversy over sexual allegations in his divorce papers.