By David Lauter, Tribune Washington Bureau

WASHINGTON — Republicans scored a significant victory in a special congressional election Tuesday, holding on to a seat in a swing district in Florida that Democrats had high hopes of capturing after a campaign that focused heavily on President Barack Obama’s health care law.

With all precincts reporting, Republican David Jolly held a 3,400-vote margin over Democrat Alex Sink in the district, which stretches along the Gulf Coast north of St. Petersburg. The returns remain unofficial until final mail-in and provisional ballots can be counted, but Sink conceded defeat in a statement to supporters shortly after the polls closed.

The Republican and Democratic parties and allied groups spent more than $12 million on the brief campaign, according to disclosure reports compiled by the Center for Responsive Politics. That’s about six times the average full-year House campaign in 2012, and an apparent record for a special election.

The money financed a deluge of television ads, robo-calls and mailers, mostly centered on national issues, which largely seemed to drown out local concerns in the contest.

Both parties saw the special election as a good opportunity to try out campaign themes they hope to emphasize this fall.

Special elections “give a test bed of issues and how they play out,” National Republican Congressional Committee Chairman Rep. Greg Walden (R-OR) told reporters Tuesday before the votes were reported. “You can test messages, and you can test strategies, and you can test your theories on voter turnout and ID.”

The Republican theory in this case was that a heavy emphasis on Obamacare would motivate conservative voters to head to the polls, making up for Jolly’s drawbacks as a candidate, which included his current profession, Washington lobbyist, and his relative lack of money.

Although both sides cautioned in advance against over-interpreting the results of special elections, that Republican bet paid off. That’s bad news for Democrats and probably will set off a new round of nervousness among party strategists and office holders as they look ahead to the fall.

The country has relatively few congressional districts that remain truly competitive between the parties. Most Democrats already have pretty much given up on winning back control of the House this year, but if they have any hope of keeping the GOP from widening its lead, they need to be able to win districts such as the St. Petersburg-area one.

Moreover, although voters in the district are significantly whiter and older than the national average, so are the swing voters in many of the states that will hold elections this year that could determine control of the Senate.

In the aftermath of the defeat, Democrats pointed to the district’s longtime Republican leanings and the heavy spending by outside groups on Jolly’s behalf.

“Republican special interest groups poured in millions to hold on to a Republican congressional district that they’ve comfortably held for nearly 60 years,” Rep. Debbie Wasserman Schultz of Florida, chairwoman of the Democratic National Committee, said in a statement.

But as Republicans cheerfully noted, Democrats and their allies from unions, environmental groups and liberal political action committees outspent the GOP side by almost $1 million in the race.

Jolly’s “victory shows that voters are looking for representatives who will fight to end the disaster of Obamacare” and restrain government spending, Republican National Committee Chairman Reince Priebus said in a statement. “In November, voters all across the country will have the chance to send the same message.”

Moreover, although Republicans did have the district’s history on their side, Obama carried the district in 2008 and 2012. In those years, voter turnout was significantly higher than in this off-cycle election, underscoring the advantage Democrats have in presidential years and the corresponding problem they face in getting their voters to the polls in midterm contests.

Sink led Jolly in mail-in ballots and other early votes, but she was swamped in the election-day turnout.

The special election stemmed from the death last fall of Republican C.W. “Bill” Young, who had represented the area for nearly 42 years. Before he became a lobbyist, Jolly had served as an aide to Young.

The winner gets just 10 months in office, the remainder of Young’s term. Jolly will have to immediately begin preparing for another fight in November, although Democrats, who will be hotly contesting the state’s governorship, are unlikely to be able to field as well-funded a challenger.

This story has been updated

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