Virginia Gov. John N. Dalton's hopes of funding Metro and highway construction with a 4 percent gasoline sales tax appeared dead today, even though the Republican governor continued to hunt frantically for support of his controversial proposal.

Although the gasoline tax bill has not been formally introduced by a lawmaker or officially debated, members of both political parties agreed it has virtually no chance of passage. Many blamed Dalton for failing to do the necessary political advance work that would have given the measure a fighting chance.

"He sort of dropped the ball," said state Sen. Adelard L. Brault (D-Fairfax), dean of the Northern Virginia delegation, whose members are now faced with finding an alternative means of raising money to finance the rapid rail system from a decidedly hostile legislature.

"The executive branch of government didn't do its homework," agreed Del. Clinton Miller (R-Shenandoah, one of the many Republicans who have refused to back the proposal of their party's titular leader.

After two weeks of little legislative activity, today was filled with trial balloons, closed-door sessions and impassioned speeches over the tax issue.

While Dalton huddled in his third-floor office with key legislators in a last-ditch effort to revive his proposal, Brault took to the Senate floor to plead with legislators to pass some form of Metro fundings.

He got support from an unexpected source -- state Sen. Edward E. Willey (D-Richmond), conservative chairman of the powerful Senate Finance Committee, which must approve any revenue bill. Willey, who just yesterday had warned the governor in private that his 4 percent gasoline tax would not pass, agreed with Brault that the state would have to make some commitment to Metro construction, although Willey was not specific.

Some lawmakers argued that only a much scaled-down proposal calling for a two or three-cent per gallon increase in gasoline taxes would have any chance of passing the tax-conscious assembly. Many Northern Virginians said, however, they believed it was unlikely that Metro would get any share of a greatly reduced tax package.

"The less money we raise, the less chance that Metro will get anything," said Del. Vincent F. Callahan Jr. (R-Fairfax).

Despite rising criticism, Dalton spokesmen insisted today that the governor has no intention of backing down from either his tax proposal or his support of Metro.

"He's bound and determined to see this thing through," said Dalton press secretary Paul G. Edwards, who promised the bill would be introduced later this week. Edwards would not disclose the name of the legislator willing to sponsor the bill.

Edwards added, however, that the governor expected legislators to offer alternative proposals and would sign any one that met his objectives of providing more funds for roads and Metro.

But some legislative leaders were predicting that no tax increase of any kind would be approved this year.

"Frankly there's no great sympathy for an increase right now," said House Majority Leader Thomas W. Moss Jr. (D-Norfolk). "The delegates may well decide we need to study this for a year."

Dalton's tax plan has been in trouble since he first proposed it during his opening address to the assembly two weeks ago Wednesday. At that time, he warned the lawmakers that the present nine-cent-per-gallon tax was not sufficient to cover the costs of building and maintaining state roadways. He also called for the state to assume 95 percent of the costs of completing Metro subway construction in Virginia -- at least $20 million during the next two years.

Before he gave the address, Dalton spent several days phoning legislative leaders of both parties to discuss the problem and line up their support. He confidently predicted he would have the votes to get some kind of increase through both legislative houses.

Dalton apparently miscalculated how unpopular tax increases are with the assembly, which has not passed a major tax measure since 1972, when it raised the gasoline tax two cents per gallon. While most Democrats, who control both houses, remained silent, many Republicans indicated they were at best reluctant to back the governor's plan.

"I never thought it had enough support to pass," said House Minority Leader Jerry H. Geisler (R-Carroll), a longtime Dalton ally.

Many legislators who were uncertain about the proposal last week made up their minds after hearing complaints over the weekend from hometown voters.

"I was at church last Sunday and a lot of people came up to me saying 'we're absolutely against this thing'," said GOP Del. Miller.

Miller and a number of other Republicans complained they had not been consulted on the proposal in advance and that Dalton had taken their support for granted. Democrats said they might have muted their opposition if the governor had provided specific details sooner about how the tax revenues would be distributed.

Without those details, few were willing to risk supporting Dalton at a time when public opposition was crystallizing. Dalton's office acknowledged it has received what spokesman Edward termed "heavy" mail "over-whelmingly opposed to a gas increase, period."

The result, said one supporter of the tax, was that "the governor's proposal has been slammed in his teeth and now he's got a huge political problem."

The Northern Virginia delegation, most of which had strongly endorsed Dalton's plan because of its Metro committment, faces a political problem as well -- coming up with an alternative method of funding Metro. Delegation members held at least two closed-door strategy sessions today and scheduled a meeting of the full 27-member group the next Monday.

In openly airing the region's Metro concerns on the Senate floor today, Brault -- who sits next to Willey -- said his "deskmate" had urged him to make a direct appeal for support to assembly.

"I know all of you have been looking on this as a Northern Virginia problem, but it's not," said Brault, who argued that moving traffic across the Potomac River was important to the entire state.

"If you want freight manufactured in Virginia to go north, you've got to make sure it can cross the river," Brault warned, noting that 'Metrorail is necessary to ease traffic congestion."

Outlining the recently signed $1.7 billion federal aid package for Metro, Brault said "not a penny" of the funds could be spent unless Northern Virginia came up with a "stable and reliable" revenue source for its share of Metro's mounting costs. "It's absolutely critical that something be done this year," he said.

Brault, interviewed later after a day of meetings, said the delegation would be looking at several alternatives to Dalton's proposal and would go ahead with plans to introduce a regional sales tax measure.

Though similar sales tax bills have been killed in previous assembly sessions, Brault said he hoped such legislation would be approved this year, particularly if the gasoline sales tax proposal is not.

"Things are going to be a little complex for awhile, but we need to have something for Metro," he said.