Democrats consider Republican Gov. Rick Scott to be one of the most vulnerable incumbent governors facing re-election next year, which gives them hope they can put one of their own in the governor's office for the first time since January 1999.

The question is who will challenge him?

The top three prospects are Sen. Bill Nelson, who says he's not planning to run; former Republican Gov. Charlie Crist, who became a Democrat less than five months ago; and former state Chief Financial Officer Alex Sink, who lost to Scott in 2010.

Despite Scott's poor poll numbers, beating him won't be easy. He has the advantage of incumbency at a time when Florida's economy is improving and his campaign will be well-financed.