Northern Virginia legislators, complaining of being "mousetrapped" in efforts to get state funding for Metro costs, decided today to try to hold off House action on a regional gasoline tax until they see how a statewide gasoline tax measures fares in committee later this week.

In a delegation meeting this afternoon, the legislators said they had been caught in the middle -- pledged to support Gov. John N. Dalton's 4-cent statewide gasoline tax to raise revenue for highway and Metro construction, yet aware that its risky chances of approval make it necessary to keep a regional tax bill in the wings.

The lawmakers also acknowledged that their only viable alternative so far, a 4 percent regional gasoline tax, is encountering strong opposition in some localities back home that want a greater say in distributing the tax money.

The regional tax bill, sponsored by Del. Warren G. Stambaugh (D-Arlington), cleared the House Finance Committee earlier this week with help from many lawmakers opposed to Dalton's statewide bill.

The governor's bill is expected to be voted on in the same committee on Friday and might come to the House floor in some reduced form next week.

"We could be forced into voting for two gas-tax bills, and this is not a pleasant thing to do," said Del. Vincent F. Callahan Jr. (R-Fairfax), chief sponsor of Dalton's bill.

Del. John H. Rust (R-Fairfax) warned the delegation that officials in Fairfax City have strong objections to Stambaugh's bill, which would send Metro tax revenues directly to the Northern Virginia Transportation Commission. He argued that a veto by that locality would scuttle the measure, which must be approved by the governing bodies of all five Northern Virginia jurisdictions.

"If it (the money) goes back to the NVTC, I don't think we're going to have a tax," Rust said.

In 1976, Fairfax City refused to go along with another Metro tax levy approved by the General Assembly.

Fairfax County's Board of Supervisors also recently voted to support the return of Metro tax money directly to localities, which would then allocate it to the NVTC. Both the Alexandria City Council and the Arlington County Board favor ending the tax revenues to NVTC.