Virginia's education lobby, anticipating a fight over school funding in the General Assembly next month, called a new state estimate of the cost of providing quality education unrealistic today and said it could force local communities to raise taxes to support their schools.

Leaders of 10 education organizations said that unless there is a resolution of the $227 million gap between what the State Board of Education has recommended in the 1986-88 budget and the amount suggested last week by a legislative commission, there could be a reversal of the state's recent education gains.

Catherine Belter of Springfield, president of the Virginia Congress of Parents and Teachers, said the recent estimate of a need for only $192 million in additional state money was calculated incorrectly. She said the estimate, by the Joint Legislative Audit and Review Commission, employed "a radical departure from methodology used the past 14 years."

The state Board of Education has said that $419 million will be needed in the next two years to fully finance the so-called "standards of quality." That figure was nearly $100 million less than an earlier estimate by the board, but it was larger than the commission's recommendation.

"We recognize this is round one," Belter said at a news conference at the Virginia Education Association headquarters here. She noted that "no political judgments have been made" on the proposals. She said Gov. Charles S. Robb and Gov.-elect Gerald L. Baliles "are committed to fully funding the standards at a level which is defensible and credible."

Belter said increased state funding during the Robb administration "contributed to the significant progress that has been made in improving the performance measurements of Virginia's schools," including a "dramatic increase" in test scores.

"Without the full amount $419 million , there will be a need for additional local money," Belter said.

Brenda Cloyd, a Wythe County teacher who is president of the education association, agreed that "many localities would have to increase taxes" if the lower estimate is adopted.

Ned Carr, assistant executive secretary of the Virginia School Boards Association, said the major victim of the joint commission's projection would be teacher salaries. "There is supposed to be enough money in the budget to support 10.2 percent salary increases in both years," Carr said.

The "standards of quality" were devised in 1972 as part of an education section adopted in the state Constitution a year earlier. They require the state's 135 local school systems to employ enough teachers to support programs meant to insure a minimum level of competency.