Harris, in an interview earlier this week with Agape Press, a Christian news service, explained why she said six weeks ago that voters should only choose "tried and true" Christian candidates.
"I was being specific in talking to them and differentiating myself from Bill Nelson, who claims to be a Christian and yet votes completely contrary to what we say we believe," she said.
Harris was not specific about Nelson's votes. In the past she has attacked him for his stand in favor of abortion rights and his opposition to a constitutional amendment on gay marriage, the Orlando Sentinel said.
"My faith is the essence of my being," Nelson said in a statement. "But it is a part of my life I don't feel I should try to take advantage of in the public square."
Harris was Florida's secretary of state during the 2000 election, when the outcome of the voting in the presidential race was ultimately decided by the U.S. Supreme Court. She was later elected to Congress.