Keen, who made abortion rights and property insurance key issues in the race, got between 65% to 70% of nonpartisan, or NPA, voters to make up for Republicans turning out in larger numbers than Democrats, said Matt Isbell, a Democratic elections analyst.
"What actually clinched the win for Democrats was this massive margin with NPAs and perhaps some Republican moderates as well," Isbell said. "If anything, this should be concerning for the GOP because it indicates a voter anger that maybe they have not understood."
The special election for the district in eastern Orange and Osceola counties was triggered when former Republican state Rep. Fred Hawkins resigned last year to become president of South Florida State College in Highlands County.
The district has an almost even collection of Democrats, Republicans and independents.