SARASOTA, Fla. — The touch-screen voting machines Katherine Harris championed as secretary of state after the 2000 presidential recount may have botched this year's election to replace her in the U.S. House, and it's likely going to mean another Florida recount.

More than 18,000 Sarasota County voters who marked other races didn't have a vote register in the House race, a rate much higher than the rest of the district, elections results show.

Sarasota County Elections Supervisor Kathy Dent defended her staff and the voting machines, arguing that the thousands of voters must have either overlooked the race — which was pushed to a second screen by a glut of minor U.S. Senate candidates on the ballot — or simply decided not to vote for either candidate in a race marked by mudslinging.

"My machines have recorded accurately for 40 elections," Dent said.

But she couldn't explain why the undervote rate in her county was so much higher than in the four other counties in the district.

Republican Vern Buchanan declared victory in the race with a 373-vote lead over Democrat Christine Jennings — less than 0.2 percent.

"Sarasota voters have been victimized by not having their votes count," Jennings said Wednesday.

Buchanan's campaign said a recount would confirm their candidate won.

Florida law requires a machine recount if the difference between the top candidates is less than half a percent. If the machine tallies find a margin of less than a quarter percent, a manual recount is conducted.

To do a manual recount for touch-screens, officials go back over the images of the electronic ballots where the machine didn't register a choice. But state rules essentially say that if the machine doesn't show that a voter chose a candidate, the voter is assumed to have meant to skip the race — it would be tough to prove otherwise.

Final results must be certified by Nov. 20.

Harris, a congresswoman since 2002, ran for U.S. Senate this year but lost to incumbent Bill Nelson.

As secretary of state in 2001, Harris had pushed for an election overhaul that outlawed the punch-card ballots involved in the 2000 presidential race recount that made Harris a GOP star. The law now required counties to use touch-screen devices or optical scan machines that read paper ballots voters filled in.

Harris spokeswoman Jennifer Marks said Harris had no comment on the House race.