First came the brochure mailed to Third District voters by the New Jersey Democratic State Committee.

The heads of Jon Runyan and his donkeys - the former Eagles lineman gets a tax break for raising them on his Mount Laurel estate - were superimposed on a photo of the Republican's gated mansion.

The unspoken message: Runyan - who hopes to unseat Democratic U.S. Rep. John Adler in November - is a wealthy tax-dodger, unfit to hold public office.

Then came Runyan's volley. Voters received an oversize postcard showing a cartoon Adler, with flames shooting from his posterior, that read "Liar, Liar, pants on fire."

In television ads and home mailings, the candidates in New Jersey's closest congressional race already are resorting to caricatures, and the general election is still weeks away.

Runyan and Adler are fully engaged so early because they have to be.

Though it traditionally tilts Republican, the Third District - which covers most of Burlington and Ocean Counties, and includes Cherry Hill in Camden County - has a strong independent streak. In 2008, voters elected Adler their first Democratic representative in decades. Last year, they swung to Republican gubernatorial candidate Christopher J. Christie.

Of the district's 456,000 registered voters, 211,750 - the largest group - are unaffiliated or belong to smaller parties and are up for grabs. There are 131,100 registered Democrats and 113,150 Republicans.

With Democrats sagging in popularity polls nationwide, Adler is running like an underdog.

He began his television ad campaign late last month with a spot that ridiculed Runyan for using the state's farmland-assessment program to reduce property taxes on his 25-acre estate.

Runyan - a first-time political candidate - last year paid a $468 tax on 20 acres where he grazes four donkeys and harvests timber, and $57,000 on five acres and his residence. The tax break is entirely legal.

The attacks were so fierce that even before Labor Day, the traditional campaign kick-off, Runyan had responded with his "pants on fire" mailing.

Adler's first TV ad launched on cable on Aug. 31. Runyan's debut cable TV ad, which began Aug. 19, attacked his opponent as a free-spending liberal clone of House Speaker Nancy Pelosi. Adler voted with Pelosi 90 percent of the time, the ad charged.

Adler's campaign says that he was named one of the nation's most independent congressmen by Congressional Quarterly, and that he voted against the bank bailout and President Obama's health care plan.

Spirited as they are, the attacks probably won't sway voters, analysts say.

"Each of them is engaging his opponent's weaknesses in a very simplistic way," said Montclair State University political scientist Brigid Harrison.

"Swing voters in the district recognize that Adler doesn't walk in lockstep with the Democratic caucus," she said. "Most swing voters in district realize that Runyan isn't as polished as Adler, but [that] he's not an idiot. Voters can filter through this."

What they want, Harrison said, are assurances that the candidates can help voters navigate a rough economy.

New Jersey voters are unhappy with Washington, but they don't believe either party is solely capable of solving the country's problems, according to a Monmouth University/Gannett New Jersey Poll in July.

Patrick Murray, Monmouth's polling director, found that 66 percent of the state's voters were dissatisfied with how things are going in Washington, but 51 percent doubted changing party control would improve government.

Those sentiments are unlikely to change much in the weeks leading to the general election, Murray said recently.

That is partly why Adler and Runyan are sidestepping party labels.

"It's a district that has voted Republican for more than a century. John Adler was the first to break that. He understands that . . . people are upset with both parties in Congress, so he's not going to identify himself one way or another. And the same goes for Jon Runyan," Murray said.

Christie won "despite being a Republican," he said.

Republicans hope to pick up 39 seats to take control of the House, which now has 255 Democrats, 178 Republicans, and two vacancies.

The Third District race is among about 80 that experts say could make a difference. The nonpartisan Cook Political Report has rated it as leaning Democratic, meaning that it is considered competitive but that Adler has the advantage.

The former state senator from Cherry Hill has a wide lead in the fund-raising race. He has raised $2.5 million compared with Runyan's $654,000, of which $300,000 came from the Republican's pocket.

Rutgers University, which so far has administered the race's sole independent poll, put Adler at 31 percent and Runyan at 25 percent in July. Third party candidate Peter DeStefano had 4 percent.

DeStefano is running under the tag "NJ Tea Party," but local tea party groups have endorsed Runyan. DeStefano's presence on the ballot still could take votes from Runyan.

Though the national party organizations have helped Runyan and Adler raise money, the parties have yet to spend much in the district. Campaign consultants say candidates must spend at least $1.7 million a week in the New York and Philadelphia television markets to have their broadcast ads seen by voters.

The Democratic and Republican congressional campaign committees still are figuring out how to allocate their funds and so far have bankrolled television ads in Indiana and Michigan, relatively inexpensive television markets.

Expenditures by independent groups, which could mount up toward the end of the local race, have been few. Only NARAL Pro-Choice America has reported expenses, according to the Federal Election Commission. The lobbying group spent about $3,500 in e-mails and letters to members advising them to support Adler. Adler and Runyan both favor abortion rights.

The two major-party candidates are set to meet in a forum sponsored by the Burlington County Chamber of Commerce on Monday and no doubt will use each the other's responses as fodder for more attacks.

Contact staff writer Cynthia Burton at 856-779-3858 or