By Barbara Liston
ORLANDO, Florida (Reuters) - Voters on Florida's Gulf Coast head to the polls Tuesday to fill a vacant U.S. Congressional seat in a special election watched by both major parties for what it portends for November when all 435 congressional seats will be up for grabs.
"It's still anybody's guess who's going to win. Turnout is key," Susan MacManus, a longtime political analyst and professor at the University of South Florida in Tampa, told Reuters less than 24 hours before polls opened.
The Rothenberg Political Report in Roll Call, a Capitol Hill-focused publication, also rated the race as a toss-up one day before the election.
Florida's is a big swing state, with 27 seats in the House of Representatives, tied with New York state for the third largest delegation in the nation, and behind only California and Texas.
A Democratic victory would be a major blow to the Republican party heading into the fall mid-term elections, as well as the next presidential race in 2016. Democrats hold the advantage in the more liberal south of the state and Republicans prevail in the conservative north, while central Florida is more evenly split.
Former Florida finance officer Alex Sink, a Democrat, has held a slight lead in the polls throughout the campaign against David Jolly, a Republican Washington, D.C., lobbyist who once worked for the late Congressman C.W. Bill Young. Young died in office in October at the age of 82 after serving 22 years.
Republicans hold a 2.4 percent edge in voter registration in Florida's congressional district 13, which lies within Pinellas County on the state's west coast. It is not certain how Libertarian candidate Lucas Overby and the 24 percent of voters who identify with no party or a minor party will affect the result.
Voters have been hit with more than $9 million worth of television advertising and other campaign material financed in large part by the national parties and partisan groups hoping a victory in this race will signal the prospect of a bigger win in the November mid-term elections.
"You can see the handprints of the national parties all over the race," said MacManus. "It almost seems as if the 2012 presidential race never ended, and just the faces and the district changed."
Sink slammed Jolly as a Washington lobbyist for special interests, while Jolly fired back at Sink for being close to President Obama and House Minority Leader Nancy Pelosi.
MacManus said an early focus on Obamacare got little traction because older voters were not affected. Sink switched to criticizing Jolly for representing a client who wanted to privatize Social Security and turn Medicare into a voucher program, changes Jolly said he does not support.
"This is a strategy I think Democrats are looking at nationally to change the focus from Obamacare to Social Security and Medicare," MacManus said.
Following the election, MacManus expects both parties to use the Tampa Bay area, the nation's 10th largest television market and home to 25 percent of all registered Florida voters, as a political laboratory to conduct focus groups on the campaign strategies.
(Editing by David Adams and Ken Wills)