Twice before, Republican Thomas M. Bolvin has used a conservative message and youthful ambition to challenge veteran state Del. Gladys B. Keating in her Fairfax County district. But powering his campaign this year is more: $50,000 of the governor's money.

The bounty has allowed Bolvin for the first time to match Keating, the Democratic co-chairwoman of the powerful House Corporations, Insurance and Banking Committee, dollar for dollar -- and full-color mailing for full-color mailing -- as they head into the final weeks of the election season.

Incumbents such as Keating have long enjoyed huge financial advantages in their reelection races because big corporations and interest groups give millions of dollars to sitting lawmakers and almost nothing to challengers.

But money from some of those same big givers increasingly is ending up in the pockets of challengers, directed there by newly flush political action committees controlled by party leaders locked in a fierce battle for control of the General Assembly. Gov. James S. Gilmore III (R) had raised $1.8 million for two legislative PACs through August and hoped to raise an additional $1 million by the election. Democrats had raised $1.9 million for their main PAC through August.

The result is financial parity, or at least competitiveness, in hotly contested races all over Virginia. These new party PACs are the most powerful forces for change in a state where the biggest business givers, lobbyists and interest groups have almost always backed the status quo at the statehouse.

"The Capitol Square crowd doesn't give to challengers," says GOP operative Ray Allen, who advises Gilmore on how to spend his PAC money.

Some of the party PACs, called "leadership PACs," are also paths to growing power for politicians such as Gilmore and U.S. Rep. Thomas M. Davis III (R-Va.). Spreading money around to candidates helps them make friends and influence elections.

Such PACs have long been active on the federal level, with national party leaders targeting key districts in battles for control of Congress. But campaign finance experts say they are increasingly prominent in Virginia and other states.

They call it a worrisome trend. These PACs concentrate power in the hands of a few leaders, and the massive transfers between PACs and campaigns can make it harder for the public to track the relationship between givers and those they may seek to influence.

"It sort of launders the money below a level of scrutiny," says Samantha Sanchez, of the Montana-based National Institute on Money in State Politics.

"When you have individual politicians building up their own piles of money . . . you have a potential for mischief," says Larry Makinson, of the Center for Responsive Politics in Washington.

Yet even Makinson and Sanchez acknowledge that these party PACs have redeeming qualities. "Any money to challengers is better than nothing, because business PACs are loath to give to anyone not in power," Makinson says.

The 20 biggest givers in Virginia legislative races -- including Philip Morris, Dominion Resources and the state's trial lawyers -- had given $2 million directly to candidates through August. But for every $1 that they gave to challengers, incumbents got $60, according to campaign finance reports compiled by the Virginia Public Access Project, a nonprofit group sponsored by The Washington Post, state news organizations and Virginia Commonwealth University.

By contrast, state party and state leadership PACs gave about $1 million to legislative candidates through August, with more than twice as much going to challengers as to incumbents. For every $1 that went to incumbents, $2.40 went to challengers.

Much of that money came originally from the same corporate givers and other interest groups that don't give a dime to challengers. In some cases, say lobbyists, these givers end up backing both sides of close legislative races as their money gets passed around.

"No longer does the person giving the money know where it's going," lobbyist Robert B. Jones Jr. says.

PACs controlled by federal leaders such as Davis also help challengers, but not as much. Through August, such PACs had given $436,000 to candidates, with nearly twice as much going to incumbents as to challengers.

The rise of these leadership and party PACs parallels the rise of a contested General Assembly in Virginia this decade. Republicans gained seats in both houses by using party money to target weak Democratic incumbents. Democrats, who have lost the state Senate, 21 to 19, and have virtual parity in the House, use their money increasingly to target the most vulnerable Republicans.

In the Nov. 2 elections, all 140 state legislative seats are up for grabs. Many Republicans believe they are on the verge of controlling the General Assembly for the first time in more than a century.

Because of the high stakes, more money -- and more party and leadership PACs -- has been pulled into the hunt than ever before. The PACs are particularly popular among Republicans. Gilmore has two. Attorney General Mark L. Earley and former governor George Allen each have one. Two of the leading Republican candidates for House speaker have their own leadership PACs.

Democrats have their Commonwealth Victory Fund, which had raised $1.9 million through August. And both Mark R. Warner, who's eyeing a run for governor in 2001, and U.S. Sen. Charles S. Robb have directed money to legislative candidates.

Democratic strategist Michael Henry says many of his party's challengers would have a hard time without this financial support. "It's a critical component of their fund-raising," he says.

Former Democratic U.S. House member Leslie L. Byrne, for example, had gotten $60,000 in party PAC money through August, which was 35 percent of the $169,800 she had raised for her challenge of Republican state Sen. Jane H. Woods in Fairfax. Woods raised a total of $316,200. Also in Fairfax, Eileen Filler-Corn got $18,000 in party PAC money, nearly half of the $44,300 she raised through August for her challenge against Republican Del. James H. Dillard II, who received $97,500 in contributions.

Many times party and leadership PACs help not with cash but with polling, printing and phone banking.

In the fight for the Fairfax district just southeast of the Springfield "mixing bowl," Bolvin, 35, is facing an incumbent well-financed by the corporations, insurers and bankers with issues before her committee.

"I'm getting money from everybody who's worked with me," says Keating, 76. "You know why? They trust me."

Bolvin, meanwhile, has transformed sections of his insurance office into a campaign headquarters. Donated wood lays stacked, ready for signs to be attached. A giant, lot-by-lot map of the district hangs on a wall, surrounded by 11 smaller maps showing how each precinct voted in recent elections, including his losses against Keating in 1995 and 1997.

Bankrolling this venture is some of his own money and that of local supporters. But his three top givers through August were a Gilmore PAC, the GOP legislative caucus's PAC and a federal PAC controlled by Davis. Bolvin said $40,000 more in polling and other services came from Gilmore in September.

In all, PACs controlled by Gilmore and other state and federal party leaders have provided about half of the $150,000 he says he had raised through September. Keating's campaign says she has raised $130,000 over the same period.

The extra help allows Bolvin to plan 18 full-color mailings to voters. And it allows him to spend time knocking on doors rather than dialing for donations. In 1997, Bolvin got nearly 49 percent of the vote, despite being outspent by Keating nearly 2-1.

"She was able to be in everybody's mailbox every single day, and I wasn't able to keep up with that," Bolvin says. "But now we're well-financed, and I'm able to be out meeting voters."