Alex Sink (D) arrives at a candidates forum in Clearwater, Fla. (Brian Blanco/Reuters)

The race to succeed the late C.W. Bill Young has stunned voters here accustomed to sleepy campaigns over the genteel and popular congressman’s four-decade tenure.

Almost twice as much money has been spent in the general election — at least $8.3 million by the nominees to fill Young’s seat, the party campaign committees and outside activist groups — than Young, a Republican, spent combined in his successful runs in the previous six races in this century.

Perhaps most surprising in the neck-and-neck race between Democrat Alex Sink and Republican David Jolly is that Sink and her allies have a decided financial edge, blanketing the airwaves with more ads than her opponent ahead of Tuesday’s vote. This money has given her the chance to win despite lingering Democratic doubts that the party’s voters will show up in a low-turnout special election.

While Jolly fought a tough primary, draining his resources for the general election, Sink hoarded her cash for an eight-week sprint to the finish. Her campaign has spent $2 million on television advertising in the general election campaign, compared with just $542,000 for Jolly, according to a tally sheet from a conservative group monitoring the spending.

Moreover, Sink has spent $1.7 million for ads on broadcast networks, the most expensive advertising real estate and what delivers the most voter eyeballs, and Jolly has spent less than $430,000 on broadcast, according to the estimate.

“Noticeably, she didn’t even come on the air until the day after the Republican primary was over,” Jolly told reporters Wednesday during a meet-and-greet with volunteers at his headquarters in this town west of Tampa. “Literally for two months it was a campaign based on fundraising, and then planning about an eight-week general election campaign. We’ve had to absorb a lot of paid media.”

Democrats remain far from confident about the outcome in this battleground district, which President Obama narrowly won in 2012. They say the district has a high variability in turnout from presidential years to midterms, and that a special election in March is even harder to predict.

In five public polls from January to the end of February, the likely voter models showed turnout would tilt between eight and 13 percentage points toward Republicans. (Those polls also have shown a very tight race between Sink and Jolly.)

Rep. Steve Israel (D-N.Y.), chairman of the Democratic Congressional Campaign Committee, has publicly and privately been warning that he believes turnout would be 13 percentage points in the GOP’s favor.

So Democrats have made voter turnout a key, particularly because about 70 percent of the ballots in the district will be cast in early voting. They are trying to take lessons from Virginia Gov. Terry McAuliffe’s successful turnout model in November, when the Democrat’s team managed to have an electorate that came close to resembling the presidential turnout in 2012 in the Old Dominion.

If you talk to the best field experts in either party, however, they will tell you that get-out-the-vote efforts are able to shift the margins only a few percentage points, enough to tip only a close race. Without a good messaging operation to mold voters’ opinions, turnout won’t matter because your candidate will be too far behind.

According to Republicans, that’s where Sink’s financial edge has come in handy, targeting Jolly on the air with unyielding attacks for his previous occupation as a Washington-based lobbyist.

The ads have accused him of lobbying to privatize Social Security — anathema in a district where nearly 55 percent of voters are older than 45 — and dismantling Medicare.

Jolly has the support of outside conservative groups, including the U.S. Chamber of Commerce, which has spent at least $1.2 million in a campaign trying to link Sink to Obama and House Minority Leader Nancy Pelosi (D-Calif.).

Still, when all the outside support is combined with the candidates’ spending, Democrats have spent nearly $1 million more on television than Republicans.

From Feb. 25 to March 3, Jolly and his GOP-aligned allies spent less than $1 million on airtime, while Sink and her allies spent nearly $1.4 million.

The best money spent in any campaign is from the actual candidates, who get the cheapest advertising rates and who can control their message. That’s made Sink’s fundraising edge, which outsiders credit to her past statewide races and name recognition, so key to this race. Jolly is a first-time candidate who used to work for Young.

When they reported finances to the Federal Election Commission in late February, Sink had raised more than $2.5 million and Jolly $1 million.

Most of Jolly’s funds had been burned in the primary, leaving him at that stage with just $182,000. Sink still had nearly $1 million to spend.

On Wednesday, an exasperated Jolly explained to reporters that he wanted to advertise about the good-government causes of clients for which he has lobbied over the years, from the “Wounded Warriors” effort for veterans to child safety.

He said he can’t. “It’s the resources,” he explained.