WASHINGTON (CNN) -- Calling Florida's District 13 election result "not valid," Democratic National Committee Chairman Howard Dean said there should be a completely new election for the seat being vacated by GOP Rep. Katherine Harris, the St. Petersburg Times reports Thursday.

"This election is not valid," Dean said in a taped interview with Bay News 9, set to air on Sunday, the Times reports. "There are 18,000 people who may have voted, and we don't know what happened to their votes."

"You can bet that if the Republicans were 500 votes short they'd be calling for a new election, and they'd be right," Dean added.

Republican Vern Buchanan was certified the winner of the race by a margin of 369 votes. His Democratic opponent, Christine Jennings, officially contested the result claiming as many as 18,000 votes in Sarasota County may not have been reported.