Former President Bill Clinton is warning that President Barack Obama's edge in the polls may not be enough to defeat GOP hopeful Mitt Romney because the Republican Party was using voter suppression techniques to target traditionally Democratic voters like African-American church members and the elderly.

"How much will the vote be lessened or reduced by the fact that in Florida except for four counties, the pre-election voting -- advanced voting -- has been cut down to and doesn't include the Sunday before the election?" Clinton told CNN's Fareed Zakaria in an interview that aired on Sunday.

The former president added that the tactic was "an arrow aimed straight at the heart of the African-American church, who pull up the church busses on the Sunday before the election and take elderly people who have no cars or people that are disabled to the polls so they can vote."

"How much will those things work in Ohio, where the legislature eliminated advanced voting unless the local election council voted for it?" he continued. "In the Republican counties, the three Democratic commissioners -- because they're not hypocrites -- voted with the Republican to allow advanced voting. In Cleveland, the three Republican commissioners voted against the Democrats so they can't have advanced voting."

"How much is all that going to affect the turnout? In my lifetime, nobody's ever done anything quite this blatant. So, I think you have to assume it's going to be close race, assume it's going to be a hard fight, and then fight through it."

Watch this video from ABC's This Week, broadcast Sept. 23, 2012.