(CNN) - Republican voters in a swing district in a purple state head to the polls Tuesday, to choose their party's nominee for a special election to fill a vacant House seat their party's held for decades.
Tuesday's GOP primary in Florida's 13th congressional district will set the stage for a March special election that some political pundits are billing as barometer for November's midterm elections.
The winner of the special election will fill the remainder of the term of Republican Rep. Bill Young of Florida, who died in October. Young, who was first elected to Congress in 1970, was the longest serving Republican in the House
The two major Republican candidates are David Jolly, who served as a former general counsel for Young and also worked as a lobbyist, and freshman state Rep. Kathleen Peters. Retired Marine Corps Brigadier General Mark Bircher is also on the ballot. The winner will face off in March against Alex Sink, the former chief financial officer of Florida and the 2010 Democratic gubernatorial nominee. Sink is the Democratic party's consensus candidate.
The district covers most of Pinellas County and parts of St. Petersburg and it's up for grabs: While Young captured 58% of the vote in his 2012 re-election, President Barack Obama narrowly carried the district. Obama also won it 2008, grabbing 51% support.
"It's rare in politics that anything other than a presidential contest is viewed as a 'must win' – but the special election in Florida's 13th District falls into that category for Democrats," writes Stuart Rothenberg, editor of the non-partisan Rothenberg Political Report, and a leading political handicapper. "Since most nonpartisan handicappers and analysts have for years expected this seat to go Democratic when it became open, a Republican victory in March would likely say something about the national political environment and the inclination of district voters to send a message of dissatisfaction about the president. And that possibility should worry the White House."
Another top non-partisan political handicapper, the Cook Political Report, agrees.
"House Democrats badly need to prove they can win an evenly split district like FL-13 in order to reclaim any momentum heading into the spring. But, even with a well-funded, well-known nominee potentially running against a former lobbyist, there is no guarantee they will prevail at a time when Obama's approval ratings are mired in the low 40 percent range," writes David Wasserman, the Cook Report's House editor.
While Jolly's lobbying career in the nation's capital could hurt him, he can tap into his large political rolodex, as he pledges to carry on his the legacy of his former boss. He's led Peters in fundraising and went up on TV with ads touting endorsement's from St. Petersburg's mayor and Bob Barker, the former longtime host of the "Price is Right."
Young's family is even split on the race: the late congressman's second wife has endorsed Jolly while his son is backing Peters.
"I think you have to regard Jolly as the frontrunner in the primary. He's the candidate who raised the most money and was able to run the most television ads in a very condensed time frame. But the primary is just the beginning. The real fight will be the March general election," say Rothenberg deputy editor Nathan Gonzales.
While the Republican candidates have fought each other, Sink has built up a formidable war chest. And she'll need it, as well as her strong name recognition, as the electorate in the March special election may be more favorable to the Republicans than the Democrats.