The Virginia House of Delegates today approved a reapportionment plan that grants Northern Virginia the 21 delegates it has been seeking, but many legislators said the proposal may never be implemented because it appears to violate Supreme Court standards.

If approved by the state Senate and Gov. John N. Dalton, today's 87-to-11 House vote could set in motion court challenges by several public interest groups.The groups have charged that the plan does not provide equal political representation because the districts that the 100 delegates would represent vary in population by as much as 26 percent.

Despite that problem, Dalton told Republican legislators this afternoon that he was inclined to approve both the House measure, and a similar one reapprotioning the 40-member state Senate. But, one lawmaker said, the governor made clear his belief that the House plan will not withstand a court challenge.

Dalton's attitude, said the legislator, is, "If anybody's going to be the bad guy, let it be the courts."

Conceivably, a court challenge could mean that the districts for this fall's scheduled House elections would be drawn by the courts, or that incumbent delegates would run from their present districts.

Spokesmen for some of the interest groups considering such a lawsuit said the House was being callous today. "This decision is irresponsible," said Common Cause lobbyist Barbara Pratt. "I just don't understand why you'd do it this way. . . ."

House leaders agreed that a court challenge is likely, but said they were hopeful that the proposal would survive. They conceded, however, that the Supreme Court has never approved a reapportionment plan with variances as large as those the House plan would create.

House Speaker A. L. Philpott said he voted for the proposal despite serious reservations because it was the only plan that could muster majority support. "If the court doesn't approve the plan, I hope they'll let us come back in session to consider it," he said.

"If we sit around second-guessing what the courts are going to do, we'll never get anything done around here," said Del. Vincent Callahan (R-Fairfax), a member of the committee that drew up the plan. "We've got our 21 seats in Northern Virginia, and that's what the people I represent care about."

Northern Virginia delegates had feared that legislative leaders from the Tidewater area would unite to strip them of added seats, as they did during the last House redistricting session 10 years ago. But the plan passed today included 12 delegates for rapidly growing Fairfax County -- two more than it has now -- while the city of Norfolk lost two seats.

Del. Elise B. Heinz, who would lose her seat representing Alexandria and Arlington under the plan, led the floor attack on it. She charged the plan, called the "bunny rabbit" proposal because one of its districts resembles a rabbit, won because it protects most incumbents.

"Everyone was tired, and nobody was prepared to face facts -- we have thrown up our hands and asked that somebody else do it for us," said Heinz, a Democrat who will lose her seat because of population losses in the inner suburbs. "I feel very strongly that what we've done is wrong in principle -- that the one-man, one-vote principle is right."

Deciding in Virginia's reapportionment dispute 10 years ago, the Supreme Court ruled that a statistical variance of 16.4 percent between districts approached the maximum allowable under the Constitution's equal protection clause, Legislators said the plan approved by the House today includes districts that range from a level of roughly 14 percent above the ideal size set by the 1980 Census to 12 percent below, or an overall variance of more than 26 percent.

Del. John D. Gray, a Hampton Democrat who chairs the House Privileges and Elections Committee, acknowledge the plan's wide statistical deviations, but argued that they had been created by natural barriers such as the Chesapeake Bay and the Blue Ridge Mountains and not by arbitrary decisions or partisan politics.

"We have not pleased everyone in this plan, but we think we have satisfied most people here," Gray said. "We think it will pass the muster of the court, despite some lawyers who advise different than that."

Del. V. Earl Dickinson (D-Louisa) complained, however, that the committee's decision to cut back representation in his area was both political and arbitrary, and resulted in the underrepresentation of thousands of citizens. According to committee figures, several counties in central Virginia with a combined population of 102,000 will, together, receive 1 1/2 delegates, while four new legislative districts with fewer citizens will be given two delegates each.

"This does not meet our constitutional requirements for equal representation," Dickinson said, "I feel like this will have to go into court and someone will recognize its discrepancies."

Gray shrugged off the criticism. "We had 101 delegates and we had to reduce it by some," he said, referring to an earlier committee plan that fell apart when panel members realize it contained one more seat than the state Constitution allows. "That was our way of doing it."