A rift in Northern Virginia's delegation to the General Assembly, highlighted by charges of secretive doings in unscheduled subcommittee meetings and by vows to hold bills hostage, has threatened Fairfax County's main legislative priority.

A House roads subcommittee, chaired by Del. Mary A. Marshall (D-Arlington), has proposed amending a bill that would lift the $10 million annual cap on how much of its own money Fairfax can spend building roads. Marshall called the measure "the great Fairfax treasury raid" and said it would cost the state millions of dollars.

Fairfax legislators angrily dismissed Marshall's objections today, claiming her amendment would ruin their bill and accusing her of acting to avenge the construction of Interstate Rte. 66, which after years of controversy was built through Arlington neighborhoods and now benefits thousands of Fairfax commuters. Sen. Richard L. Saslaw (D-Fairfax) threatened to delay any bill Marshall sponsors until she backs down. Consideration of one of her bills was postponed in the Senate today.

"It's just her way of trying to block the roads bill," Del. Vivian E. Watts (D-Fairfax) said of the Marshall amendment. "It's her way of continuing the I-66 fight."

"I think the Fairfax people are being unfair to me in trying to make it a personal grudge," Marshall responded. "They could build hundreds of miles of roads that the state would be stuck with."

Two years ago, the General Assembly gave Fairfax the right to sell bonds, with voter approval, to finance road widenings and improvements, helping pick up what had always been a state responsibility. Although the state highway department still maintains all roads in Fairfax and most of Virginia, its funds have not kept pace with roadbuilding needs in fast-growing counties like Fairfax and Prince William.

Fairfax voters have approved the sale of $55 million in road bonds, but the county now may spend only $10 million each year. With projects promised to supervisors in all eight county districts, officials said the limit is too low and asked the state to remove the limit.

Not all Fairfax legislators are enthusiastic about lifting the limit. "All of a sudden they're in competition with the state, and it's a giant pork barrel," Republican Del. Robert E. Harris said earlier in the session. "As a homeowner paying taxes in Fairfax County, I would worry that the program seems to be getting out of control."

Saslaw said the legislature should be grateful Fairfax is willing to chip in for roads Virginia would otherwise have to build, and Watts said Fairfax can spend no more than its voters approve. "This is not some kind of a blank check," she said.

Marshall argued that any roads Fairfax builds or widens eventually will have to be maintained by the state. "I suspected from the beginning they wanted to unload a tremendous cost on the state," Marshall said. "It won't hit now, it will hit in 10 or 15 years . . . . It's not fair for one county with that amount of resources to obligate the funds of the state."

Marshall's amendment, which will come before the House Roads Committee on Thursday, would force the county to maintain any roads it builds or improves. Some legislators and county officials said today they hope that Marshall will be willing to back down.

Fairfax can't afford the Marshall amendment, Fairfax Board Chairman John F. Herrity said. "It's another example of outright insanity. They won't give us the money, and they won't let us spend our own."

The amendment was put forward at a subcommittee attended by Marshall and one other legislator, which Fairfax officials said took place a day before it was scheduled. Marshall said she told Saslaw when the bill would be considered.