Democrat Travis Childers and Republican Greg Davis will meet in a run-off May 13 to fill the unexpired term of Roger Wicker, who was appointed by the governor to fill the seat left vacant by Sen. Trent Lott.
The run-off is necessary because no candidate received a majority.
Six candidates were on the ballot, but only four were serious contenders. They were Childers, Davis, independent Wally Pang and Green Party candidate John M. Wages, Jr. Democrat Steve Holland and Republican Glenn McCullough tried to withdraw from the race, but the ballots already had been set.
Unofficial tallies Tuesday night had Childers with about 49 percent of the vote, compared to Davis' 46 percent.