He was to be followed by the other hopeful, Andrea Grubb Barthwell, a former deputy drug czar in the Bush administration.
Party officials said the committee choosing the candidate wanted to emerge with a single candidate to replace Jack Ryan in the race against Democratic rising star Barack Obama.
Keyes is an East Coast conservative who hasn't lived in Illinois. Barthwell is a Chicago-area physician who has a history of contributing to Democrats
Either choice to go up against Obama almost assures Illinois will send Washington only its fifth black senator in history.