Redskins owner Daniel Snyder yesterday declared victory in his campaign to win three seats on the board of Six Flags Inc., bringing him closer to his goal of controlling the theme park company. An independent firm will now tally up shareholders' votes and certify the results.

Owners of more than 57 percent of the company have thrown their support behind his plan to revive Six Flags' fortunes, Snyder said.

"Stockholders have sent a clear message that it is time for change at Six Flags," he said in a statement.

Snyder's announcement marks the culmination of a three-month effort to persuade Six Flags' shareholders to remove chief executive Kieran E. Burke, Chief Financial Officer James F. Dannhauser and board member Stanley S. Shuman and to install Snyder, former top ESPN executive Mark Shapiro and home builder Dwight C. Schar on the board instead. Snyder, the company's largest shareholder, needed the support of owners of a majority of Six Flags shares.

Snyder wants to replace Burke as chief executive with Shapiro, but his victory, if confirmed, lands him only three seats on the seven-member board, not enough to force Burke out and vote in Shapiro. Only the board can hire and fire the chief executive, according to the company's articles of incorporation and law in Delaware, where Six Flags is incorporated.

Voting on Snyder's proposals got underway last month. Shareholders can vote in favor of Snyder's proposal, against it or not vote at all -- which would be counted as a vote against. They have until on or about Dec. 24 to change their minds, but Snyder's announcement yesterday asserts he has commitments from enough investors to prevail.

Separately, in a filing with the Delaware Chancery Court, Snyder yesterday asked the courts to validate the voting results -- a move often made in anticipation of further litigation, said Lawrence A. Hamermesh, a corporate law expert.

Six Flags officials did not concede defeat, adding they would not comment further on the matter until after both sides had a chance to review and to challenge votes and the results were certified. They said that they would carry on with a potential sale of the company, a process they began in August, shortly after Snyder launched his bid for the board seats.

Snyder and Shapiro, who met at an NFL broadcast meeting several years ago, spent the past several weeks on the road, meeting with shareholders and trying to convince them that current management has done a poor job of running Six Flags and has not done enough to reverse a decline in revenue and attendance in recent years. They laid out plans to overhaul the company's operations and marketing and to make the chain's 30 parks more family-oriented. The two men have hinted at ambitions beyond amusement parks and a desire to build a family entertainment company.

Six Flags officials have gone on a counteroffensive with shareholders, saying a recent improvement in the company's financial performance was proof their strategy was working. They urged shareholders not to endorse Snyder, calling his ideas "risky" and "ill-conceived."

In recent weeks, Six Flags managers had urged shareholders to wait a few weeks longer before making up their minds about Snyder's plan so they could compare his offer with that of a prospective buyer. They expected to have a bid by year's end and said the only threat to a sale would be Snyder and his slate getting on the board.

Snyder said previously that if installed on the board he and his team would not block a sale of the company if a promising offer came along. In materials he sent to shareholders, however, he argued that it was not the right time to sell the company.

Snyder did not indicate publicly yesterday which investors had backed him. His spokesman did not respond to phone messages and e-mails.

Snyder, who controls 11.7 percent of Six Flags shares, needed the backing of only a handful of other investors, including Microsoft Chairman Bill Gates, who owns 11.5 percent, and Omaha fund manager Wallace R. Weitz, who controls 10.6 percent. Until yesterday, only New York investor Simon Glick, who owns about 9.8 percent of the company, had said publicly that he would back Snyder. Representatives for Gates did not return phone messages. Weitz declined to comment.

Shares of Six Flags closed at $7.46, down 1.8 percent.

Staff writer Thomas Heath contributed to this article.

Redskins owner Daniel Snyder wants to revamp Six Flags' operations and marketing and make the chain's 30 parks more family-oriented. Mark Shapiro, shown, is Daniel Snyder's choice for Six Flags chief executive.