Republican legislators from Northern Virginia rolled out a plan yesterday for financing $3.5 billion in highway and transit projects across the state, including $865 million for a rail line along the Dulles corridor.

The announcement was yet another salvo between the parties over traffic congestion, rapidly emerging as the hottest campaign issue ahead of the November legislative elections. Several hours later, Democratic members of Congress trumpeted their own federal initiative to raise transportation dollars.

Standing in an Arlington park beside Interstate 66, Sen. Charles S. Robb (D-Va.), Rep. James P. Moran Jr. (D-Va.) and Del. Eleanor Holmes Norton (D-D.C.) announced they would reintroduce a bill creating a regional authority that would set transportation priorities and be able to levy taxes and tolls.

The Republican legislators, who held their news conference in a Tysons Corner business park overlooking the Dulles Toll Road, had detailed a plan that would represent the state's most ambitious effort to borrow for transportation projects.

They said their 20-year bonds would not require new taxes and could be financed from budget accounts worth $225 million that this year are paying for items GOP legislators say are not expected to recur. This would include about $93 million budgeted for addressing the year 2000 glitch in state computers as well as other funds being spent on historic landmarks, payments to non-state agencies, schoolbooks, training for teachers and the Richmond convention center.

"This money can be dedicated for a bond issue that would work, that is responsible, that is in the context of conservative government in Virginia," said Del. Vincent F. Callahan Jr. (R-Fairfax), who co-chairs the House Appropriations Committee. "It is new ground we are breaking . . . but we can't operate like in the dirt-road days of the '30s."

Under the proposal, proceeds from the plan would cover the state's share of a nearly $2 billion project to extend Metrorail through Tysons Corner and along the Dulles Access Road as well as pay for a new 350-space commuter parking lot in Prince William County.

Other major projects include the completion of Route 58 in southern Virginia, construction of a new highway between Virginia Beach and Chesapeake, widening of Interstate 64 in Tidewater and improvements to I-81 in western Virginia.

"We have to provide good transportation for the myriad of businesses we've attracted to Virginia and we want to continue attracting to Virginia," said Del. Jeannemarie Devolites (R-Fairfax).

Although Northern Virginian Republicans said they have been told by Gov. James S. Gilmore III's staff that the budget includes more than $340 million in nonrecurring spending that could finance bonds, the legislators would not detail all the specific items. They stressed that it would be up to the governor to determine which spending to redirect toward road and transit projects.

But so far, Gilmore has refrained from endorsing the financing proposal by his fellow Republicans. His spokesman, Mark A. Miner, said the governor would review it along with other proposals in crafting an approach for addressing traffic congestion.

Craig K. Bieber, executive director of the Virginia Democratic Party, said the bond plan could be a cover for cutting state programs that Republicans consider a low priority. "They're claiming these are nonrecurring costs," he said. "How do we know they are?"

He said Virginia motorists would see traffic relief sooner under a plan unveiled last week for using $71 million a year in recordation tax money and half the annual state budget surplus for road and transit improvements.

Underscoring the sharp political edge to the debate, the Democratic members of Congress attacked Gilmore at their news conference for opposing any new authority that could break his no-new-taxes pledge. "The only real obstacles that remain are two," said Moran. "The first obstacle is ignorance. The second is Governor Gilmore, and I can let you reach your own conclusion on why."

The Democrats cited a state legislative projection that Virginia is falling behind its transportation construction needs by $1.5 billion a year. The Washington region, they said, is lagging by $500 million a year. "All we want to do is be able to use our own money to solve our own problems," Moran said.

The bill, which failed last year, faces an uphill fight in Congress again, sponsors acknowledged. While the lead lobbyist for the Maryland Chamber of Commerce attended yesterday's event, no state elected officials were present. Sponsors of the bill acknowledged concerns by Marylanders about how a regional authority would allot resources.

Robb said the bill would let the region's elected officials decide "what we want to do . . . and how we want to pay for it" by consensus, with approval by both states' governors and the District's mayor.

"It could include sales taxes, it could include fuel taxes, it could include tolls," Robb said. "We accept the fact if you want significant transportation and environmental improvement in the air, you're going to have to pay for it."

On another front in the political war over transportation, Dels. Robert G. Marshall and Michele B. McQuigg, both Prince William Republicans, weighed in this week with their own proposal to ease congestion on I-95. In a letter to state Transportation Secretary Shirley Ybarra, they urged that the highway shoulders between the Prince William Parkway and Newington be used as additional lanes during rush hour. The plan would require approval from the federal government.