Parents who have lobbied for years for a new high school in South Riding are organizing to get their community to the polls Tuesday to approve the financing to build it.

Cheryl Bacak, president of Neighbors for Education, a group made up primarily of South Riding parents, said she has activated her e-mail list of several hundred people to encourage the school's supporters to vote. Group members will also hand out fliers encouraging yes votes at South Riding's two polling places and, manpower permitting, at polling places in Ashburn.

Bacak said residents in Arcola and other Dulles South communities will also be lobbying their neighbors to approve the bond issue.

In addition, the South Riding homeowners association has mailed fliers to every home in the development with information about the vote -- without advocating a yes or no -- and has hung banners in the area reminding residents to vote on Election Day.

"I'd like to see 100 percent turnout," Bacak said. "We all know that's not possible. But we can sure hope."

Loudoun County voters have approved every school bond in the past 11 years. Last year, 72 percent of voters passed an $83.1 million bond issue to build four elementary schools and a middle school.

But this year's bond issue has been more controversial. Voters are being asked to take on almost $119 million in debt to build high schools in South Riding and Brambleton and to renovate Broad Run High. The two high schools got on the ballot simultaneously only after a 5 to 4 School Board vote and public hearings that drew hundreds of parents, many of whom opposed building two high schools at once.

"This has been the most debated, discussed and dissected issue this School Board has dealt with in our term. . . . At this point, it's up to the voters to decide," said board member Patrick F. Chorpenning Jr. (Mercer), a South Riding resident who has been the high school's most vocal proponent on the board.

People on both sides of the issue said that heavy voter turnout in South Riding could make a difference in a year with no gubernatorial or presidential election to increase turnout in other parts of the county.

"If they get everyone in South Riding to go out and vote yes, that could make the difference," said David Baroody, a parent who lives in Broadlands and who was vocal in his opposition to building both schools at once. "But I think if people are sensible in this decision, they'll vote no."

Bacak said she hopes that voters across the county would support the bond but agreed that turnout in South Riding could be critical.

"If the bond goes down, a lot of kids are going to suffer," she said. "There's a lot at stake."

South Riding residents said they have been waiting for a neighborhood school for years and argued that growth in the area around Route 50 in eastern Loudoun justifies building a high school there to open in 2005. Opponents argued that the population projections justified only one high school -- in the Brambleton subdivision built to relieve growth in Ashburn.

School Board member J. Warren Geurin (Sterling) said the situation reminded him of a similar one 26 years ago when voters across the county opposed the financing of Park View High in Sterling but the bond issue passed on virtue of votes from the Sterling Park community.

But Geurin, who opposed putting both schools on the bond, said the county has grown too large since then for one community's votes to count so heavily.

"If you look at the number of registered voters, South Riding is not going to make a difference," he said.

There are 6,061 registered voters in South Riding, out of 119,774 across Loudoun, said Betsy Mayr, secretary of Loudoun's electoral board.

Geurin said he was not aware of any organized effort to oppose the school bond.

Baroody said he e-mailed about 400 supporters who had lobbied against putting both schools on the ballot to remind them of the issues but said he was doing no further organizing.

David Wilkinson, a Hamilton resident who wrote a letter to the editor to several newspapers -- including The Washington Post -- in opposition to the bond, said his group, Citizens for Affordable Schools, also mailed a letter to members of Loudoun's Republican Party urging a no vote. Wilkinson said, however, that he plans no further lobbying.

Geurin noted that the bond issue is paired on the ballot with an initiative to raise the sales tax in Northern Virginia by a half-cent to pay for transportation projects.

"My assumption is that motivated voters coming in to vote against the sales tax referendum would take a pretty dim view of a School Board asking for the financing for two high schools at the same time," he said.

At Broad Run High, where the school's renovation is tied to the two multimillion dollar high schools, PTSO President Kathleen Cowley said her group had e-mailed every parent to remind them of the election.

"I'm a little concerned," she said. "We're a small sector of the whole community. We're going to need every body in this area and then other citizens to realize that Broad Run really does need these renovations."