The Northern Virginia suburbs have become a key battleground in Tuesday's House of Delegates elections, as Republicans fight to keep their 60-seat majority against a Democratic Party, confident they will gain seats for a second straight election.

Both parties have poured hundreds of thousands of dollars into six fiercely competitive races in the region, including a contest in Prince William County between Del. Jeffrey M. Frederick (R) and Supervisor Hilda M. Barg (D) that has surpassed the $1 million fundraising mark, unusual for a state House campaign.

Democrats, riding high off Gov. Mark R. Warner's popularity in statewide polls, have aggressively attacked Republican incumbents, saying they are out of step with mainstream Virginians on pocketbook and budget issues, while promising to continue Warner's legacy of funding education and remaining fiscally responsible.

Republicans have parried with promises to curb state services for illegal immigrants, fund transportation initiatives without raising taxes, continue a phase-out of the state's car tax and offer a fresh style of governance that is in tune with Virginia voters. They are challenging several Democrats in Fairfax and Alexandria.

Democrats, who picked up three seats in 2003, have set an ambitious goal of snaring three more, with a strategy of running against lawmakers who opposed Warner's signature achievement: the $1.5 billion tax package that raised money for education, health care and public safety. If Democrats can win a few races, they will gain an extra seat on key House committees. There are 38 Democrats in the House.

And while Republican leaders have said they are confident they can win seats on the Northern Neck and in southwest Virginia to offset any potential losses in Northern Virginia, they have focused much of their attention on trying to hold off a Democratic charge in the north.

Yesterday, as mailers arrived in homes and campaign workers knocked on doors throughout Northern Virginia, candidates fanned out to push and prod residents to vote on Tuesday. Del. David B. Albo (R-Fairfax) stood outside a Lorton supermarket, shaking hands with constituents. The 12-year delegate is in one of the races in the Washington suburbs that is being watched carefully by politicians and observers.

He is facing first-time candidate Gregory A. Werkheiser in one of five races in the region that has topped $750,000 in fundraising. Werkheiser (D) has run a campaign largely criticizing Albo for failing to support the legislature's tax package from last year. Like many Republicans, Albo has shot back that the package did nothing to help improve the state's road and rail network.

"What he's talking about is a tax increase that didn't put one penny into transportation" and sent money to southwest Virginia, Albo said. "No money for transportation, and it was a money grab."

Meanwhile, Werkheiser, who closely ties himself to Warner and his success, participated in a news conference yesterday, calling for tougher laws for child abusers.

He also has been critical of Albo's stances against illegal immigration, saying that Albo's solutions do not get to the heart of the problem.

"Is this thoughtful dialogue about realistic solutions or is this grandstanding?" Werkheiser asked before an afternoon of door-knocking. "I think most people are going to think the latter."

Political leaders in both parties said that the Northern Virginia races -- like the statewide races -- could turn on external factors. Voters in the Washington suburbs, they say, tend to be influenced by the political mood in Washington, and the general dissatisfaction with President Bush, according to recent polls, and Republican Party troubles could have a broad impact on local races.

"If the contrast is between how things are going in Richmond and how things are going in Washington, I think most people are saying: 'Let's take the state path,' " Warner said recently in an interview. "From what I've seen so far in . . . House of Delegate races, it seems to be more pronounced in Northern Virginia."

Republican leaders agreed that their fortunes in several key races in the Washington suburbs probably will be influenced by how closely voters associate the Virginia GOP with Republicans on Capitol Hill.

"A week or so ago when the base was upset about the Supreme Court nominee and when gas prices were higher than they are today, I think we all were concerned," said Majority Leader H. Morgan Griffith (R-Salem). "We feel a little better now . . . but it's fair to say we're guardedly optimistic about what going to happen in Northern Virginia."

"The question is, how strong are the winds? Are they gale-force or hurricane winds?" said Rep. Thomas M. Davis III (R-Va.), who was campaigning with Albo, referring to the negative news from Washington.

Several Republican candidates in Northern Virginia have expressed concern about their party's troubles in Washington and how that could affect their races. In a closely watched contest, Republican Michael J. Golden is taking on Democrat Dave W. Marsden for a Fairfax seat vacated by former delegate James H. Dillard II.

"Republicans are very frustrated with Bush for a lot of different reasons," Golden said recently as he was walking through the district. Asked whether he was concerned about Bush's impact on his race, Golden responded with a chuckle: "Wouldn't you be? I laugh about it because I'm sad about it."

Golden opposed last year's landmark tax increase package. He supports a capping of real estate taxes similar to a plan offered by Republican gubernatorial candidate Jerry W. Kilgore.

Indeed, his comments about Bush were confirmed in a conversation with a prospective voter minutes later.

"I did vote for Bush -- not sure if I'd do it again," said Mike Champagny, 36, of Fairfax. "He's been hit with a lot of hard issues that are making him look pretty bad. But even so, I've been disappointed."

To capitalize on dissatisfaction with the president, Democrats in Northern Virginia have tried to tie local Republicans to the national party. Marsden has attempted to paint Golden as out of touch with a swing district that by most accounts is evenly split between Republicans and Democrats. Marsden has campaigned with Dillard.

"I'm a Republican, he's a Democrat, but I'm supporting him," Dillard told voters on a recent Saturday afternoon.

Marsden has said that Golden's plan to cap real estate assessments would be irresponsible and leave local governments hamstrung.

First-time candidate Gregory A. Werkheiser, joined by his wife, Marion, campaigns at the home of a supporter. He will face Del. David B. Albo (R-Fairfax) on Tuesday.Del. David B. Albo (R-Fairfax), a 12-year veteran of the House, speaks with Barbara May and her granddaughter Kelsey, 3, outside a Lorton supermarket.