Leaders of a campaign to ask District voters to approve the legalization of slot machines vowed yesterday to appeal a decision by the D.C. elections board to throw out thousands of petition signatures aimed at putting the gambling initiative on the Nov. 2 ballot.

Businessman Pedro Alfonso, who chairs a political action committee formed to push the slots proposal, said the board erroneously accused some petition circulators of making false statements and misrepresenting the gambling plan as a harbinger of jobs, improved public schools and better health care for the elderly.

"Our intent is to file an appeal" by tomorrow, Alfonso said in an interview. "We are concerned about the board's decision to strike petitions based on misrepresentations."

The decision, delivered late Tuesday by the D.C. Board of Elections and Ethics, wiped out more than half of the 56,000 signatures gathered during a high-pressure, five-day drive that ended July 6, according to slots supporters. Without those signatures, Alfonso said he is "fairly certain" that the board will rule today that the campaign has an insufficient number of valid signatures to qualify for the ballot.

In anticipation of that verdict, Alfonso said slots supporters are analyzing the board's ruling, preparing an appeal and hoping the D.C. Court of Appeals will expedite the case so city residents can have a chance to vote on the gambling measure this year.

"I'm in the fight, and I'm in the fight till the fat lady sings," Alfonso said. "Our resolve is to see an initiative of this sort get on the ballot in November" or, failing that, "in the future."

Anti-slots activists, who have been working for two months to block the gambling initiative, vowed to intervene in any appeal, which would pit slots supporters against the elections board. The activists also urged Alfonso and his attorney, John Ray, to give up the fight.

"I would urge them to stop. They have done enough harm to our city," said lawyer Ron Drake, who filed one of two challenges that launched the elections board's investigation of the petition drive. "They can't win. They are not going to win. I will confront the committee in the Court of Appeals, and the people of our city will win."

If approved by voters, the slots initiative would authorize the installation of 3,500 slot machines on a 14-acre site in Northeast Washington at New York Avenue and Bladensburg Road. The initiative is being funded by a group of St. Croix entrepreneurs who are proposing to build and operate a $510 million entertainment complex on the site, which they say would create 1,500 jobs.

The project would generate $765 million a year in slots revenue, according to supporters. Under the initiative, a quarter of the money would be given to the D.C. government, and the city would be urged to use the cash to pay for public education and prescription drugs for the elderly.

From the start, slots supporters have sought to play up the benefits of gambling revenue. When they filed the initiative with the elections board in April, the proposed title was the "Jobs, Education, and Healthcare Lottery Expansion Initiative of 2004." The elections board renamed it the "Video Lottery Terminal Initiative of 2004" but approved a reference on the petition forms to schools and prescription drugs.

Anti-slots activists challenged that decision, and in late June, a D.C. Superior Court judge ordered that the language be removed. The judge did not address whether petition circulators could discuss that aspect of the referendum. According to testimony before the elections board, many circulators were trained to focus on those subjects rather than on gambling. When the petition drive hit the streets, Rob Newell, one of the St. Croix financiers, paid for yellow T-shirts emblazoned with the slogan "Sign up for Jobs, Schools and Health Care."

On Tuesday, elections board Chairman Wilma A. Lewis said some circulators told voters that the initiative is "about schools and health care" rather than about gambling, an illegal misrepresentation of the proposal. Acting for the three-member elections board, Lewis threw out signatures gathered by those circulators, who accounted for about half the total.

Ray quickly took issue with the board's ruling, calling it "absurd" to bar discussion of an important aspect of the initiative. "I do believe the board misapplied the law in several circumstances," he said.

Kristina Wilfore, executive director of the Ballot Initiative Strategy Center in the District, said an appeal by slots supporters could be viewed sympathetically by the court.

"Courts and other bodies overseeing these kinds of petition drives take the issue of not disenfranchising voters very seriously, even where there is proven fraud," Wilfore said. "So how those First Amendment issues weigh against what was clearly fraud will be what is at stake in any kind of appeals court decision."

Staff researcher Bobbye Pratt contributed to this report.