The replacement to fill the late Bill Young's seat in Congress will be chosen after a special election in Pinellas County. Young died in October after serving in Congress for more than 40 years.
Polls opened at 7 a.m. Tuesday and will close at 7 p.m.
The race for the 13th Congressional District seat has garnered national attention and nearly $9 million in outside money. The district is considered a tossup, and ads for Democrat Alex Sink and Republican David Jolly have inundated mailboxes and airwaves in recent weeks. A third candidate, Libertarian Lucas Overby, is also running.
The race has also drawn millions in outside money. According to figures compiled by the Center for Responsive Politics, groups such as political action committees and conventional party committees have spent a total of $8.8 million on the race in 2014 as of Monday.
The candidates have also raised millions of dollars. Sink raised $2.5 million and Jolly $1 million, according to the nonpartisan research group.
Voters in this stretch of beach towns and retirement communities provide the first 2014 campaign test of whether Democrats can counter GOP attacks on the president's health care overhaul. The district comprises much of Pinellas County along Florida's Gulf Coast, with the exception of the city of Tarpon Springs and a portion of downtown St. Petersburg.
As of Sunday night, nearly 125,000 people in Pinellas County had already voted, a total of 26 percent of the eligible voters. Nancy Whitlock, a spokeswoman for the Pinellas County Supervisor of Elections, noted that two days before the Jan. 11 primary for the congressional race, a total of 18.7 percent of the voters had turned out.
She said that the turnout is also greater than the last special congressional election in Florida, which was held in April 2010 in the Fort Myers area. During that election for the 19th Congressional District seat, 15.2 percent of eligible voters cast ballots, she said.