In New York City’s political terrain, Staten Island has long had a unique topography. Just as its cul-de-sac streets and manicured lawns are distinctive, so is its political reputation.

While the rest of the city has routinely elected Democrats to Congress, Staten Islanders have, since 1978, ensured that the city sent at least one Republican to Washington.

Now, however, Democrats, who are coming off last year’s loss of four seats in the Senate and three in the House, are aggressively attempting to make inroads in historically GOP territory. On their national hit list for the 2006 midterm elections is Republican Rep. Vito Fossella, whose district includes all of Staten Island and a piece of Brooklyn.

The chairman of the Staten Island Democratic Party, Assemblyman John Lavelle, called Mr. Fossella “very vulnerable.” He said last year’s election, in which Mr. Fossella’s challenger, Frank Barbaro, a retired judge, garnered more than 40% of the vote, was not only encouraging, but also gave the party a foothold in the area that will position it better for the upcoming race.

“Frank Barbaro is the most liberal person who’s ever run on Staten Island,” Mr. Lavelle said during a phone interview last week. “He ended up with 42% of the vote during a year that Bush carried Staten Island. If that’s not an indication that Vito is vulnerable, I don’t know what is.”

New York Democrats are not alone in their efforts to win the Fossella seat. The Democratic Congressional Campaign Committee has already started priming the 13th Congressional District for 2006.

Over Memorial Day weekend, it paid for radio advertisements attacking Mr. Fossella’s vote against a measure that would have expanded Tricare, the military health-insurance program. Mr. Fossella was one of about a dozen candidates that the national campaign committee targeted in the advertisement, though officials at the committee would not say which stations aired it or how much the organization paid for the spots.

The organization also commissioned a poll that matched Mr. Fossella with three potential Democratic challengers: City Council Member Michael McMahon, Assemblyman Michael Cusick, and state Senator Diane Savino. According to the Staten Island Advance newspaper, the poll, which was conducted over two days in May, showed that Mr. Fossella would best them all by margins ranging from 15 to 25 percentage points. Also, 43% of voters surveyed said Mr. Fossella deserved to be re-elected.

Democrats said the results showed that their undeclared challengers are competitive and that less than half of voters want Mr. Fossella representing them in Washington. Mr. Fossella said that “even their own poll” had him far ahead of their favorite candidates.

In addition to the Congressional Campaign Committee’s efforts, the Seattle-based Democratic Advancement Political Action Committee, a group created in 2002 to raise money for Democratic candidates nationwide, plans to organize grassroots field operations once a Democratic candidate is chosen.

The group’s president, Thomas Cramer, said that though the organization “started from nothing three years ago, we are like the little engine that could.”

“We are going to be a lot more aggressive in that district this time around,” he said. “I expect to win it.”

Yet as the Democrats make the case that Mr. Fossella is “out of step” with his constituents, they acknowledge the uphill battle to defeat an incumbent. Mr. Fossella, who grew up on Staten Island, was first elected to the City Council in 1994 and has never lost an election. Rather, he has won by wide margins. Meanwhile, in his nearly eight years in Congress, he has voted to lower taxes and increase military spending in a borough with a high percentage of civil servants and veterans.

“They can try to create a perception as much as they want to, but the reality is that even on Staten Island, we received almost 65% of the vote,” Mr. Fossella told The New York Sun, referring to his last race. “They are almost trying to make an overwhelming victory look like a loss. I would take a 60% victory every day of the week.”

There is no doubt that Mr. Fossella will have the backing of national Republican organizations and will be receiving contributions from all over the country.

“Even as we speak they don’t have a candidate, they don’t have a campaign, they haven’t raised one dollar,” Mr. Fossella said.

Yet as approval ratings for President Bush and the Republican Congress slump, Democrats have portrayed Mr. Fossella as a lackey for the House majority leader, Thomas DeLay. For months they hounded the Staten Islander to state his positions on Mr. Bush’s proposal for private Social Security accounts and on the president’s position on stem-cell research, two areas on which his constituents largely disagree with the president.

This month Mr. Fossella came out against both of the president’s proposals, first voting against the ban on federal funds for embryonic stem-cell research, then coming out against “progressive indexing” in connection with Social Security.

When asked whether he felt pressured to reject Mr. Bush’s positions because of the increased public criticism from opponents, he said he has always been an independent thinker and was simply doing what was in the best interest of his constituents.

Mr. Lavelle and others said Mr. Fossella has been more visible than ever at community events in his district because of their opposition. Mr. Fossella has also reportedly met with several influential labor leaders in his district office – which many say is unusual for him.

Democrats have interviewed and screened four potential challengers, but are also trying to rouse the borough’s Democratic leanings elsewhere. Local Democrats have recruited a challenger, Craig Schlanger, to take on a Republican member of the City Council, Andrew Lanza, who won two years ago with more than 70% of the vote.

A longtime Democratic political consultant and pollster, Bernard Whitman, is, with two other partners, running a new firm that is talking to local Democrats about getting involved in Mr. Schlanger’s race.

“He’s a young guy that can start to shake things up,” Mr. Whitman said of Mr. Schlanger, 27, who works with families of children with developmental disabilities. “It’s an opportunity to start challenging Republican ideals and engaging Democrats. This race will definitely lay the groundwork for challenging Fossella in ’06.”

Though the party not in the White House has historically picked up seats during midterm elections, this year more Democrats are up for reelection than Republicans. The challenge for both parties will be holding onto their seats while adding some more to their column.

Mr. Fossella is just one of many candidates around the country who may be feeling the heat associated with the upcoming elections. Though he acknowledged that Democrats seem more aggressive than in the past, he said that he felt confident he would prevail and that the competition has even energized his supporters.

“Up until today when I have gone before the voters, they have put their trust in me,” he said.

“Don’t get me wrong, we are not taking any election for granted,” he said. “We are going at 110%, as we’ve always done.”