Gov. James S. Gilmore III savored the glitziest stop in a record-shattering round of fund-raising tonight, welcoming former president George Bush and Virginia's Republican elite to a dinner that aides said will help send nearly $2 million to his political action committee in time for the Nov. 2 legislative elections.

With blocks of tickets as high as $25,000 for beef tenderloin dinners and souvenir photos with the nation's most recent GOP president, Gilmore celebrated his 50th birthday at a downtown hotel with 300 supporters and marked another milestone in a relentless push for a new majority in a General Assembly ruled by Democrats for more than a century.

"Virginia Republicans, winning a majority comes down to this: Will we be overcome by the final ramshackle remnants of a fading single-party system?" Gilmore said in after-dinner remarks.

"Not only must we win, you can take this to the bank--we will win," Gilmore said. "I ask you to keep building the momentum. . . . These are local races. Winning them and a Republican majority is in your hands, not mine."

Bush said, "I want to see this state solidify and improve on this marvelous direction it's made. I can think of no better way to help Virginia secure a better future than to give this governor . . . a legislature that shares his forward-looking conservative principles."

M. Boyd Marcus Jr., Gilmore's chief of staff and an architect of his strategy to capture the 100-member House of Delegates, predicted that the GOP will secure at least 51 seats and perhaps as many as 55 "if things swing our way." Republicans already enjoy a slight edge in the 40-member state Senate.

"We stand at a point in history," Marcus said in an interview earlier today. But, he added, "The world will go on, whoever wins or loses."

The atmosphere at the Jefferson Hotel, a turn-of-the-century monument to luxurious living, was fit for a winning team--or at least one that had started the week with a successful fund-raiser in Bristol, followed by another Wednesday night in Roanoke with Laura Bush, wife of Texas Gov. George W. Bush.

Gilmore's series of fund-raisers ends Tuesday with two featuring George W. Bush, first a luncheon in Norfolk and then a dinner at the McLean home of real estate developer Dwight C. Schar and his wife, Martha.

The evening event alone, which is designed to tap Northern Virginia's affluent high-technology community, is expected to raise an estimated $400,000, Gilmore aides said. Virginia's governor has endorsed his Texas counterpart for president.

Democrats will use some star power of their own as both parties begin the final push for legislative seats. Two weeks from tonight, President Clinton will be the honored guest of Alexandria Democrats at their seventh annual dinner honoring the memory of Robert F. Kennedy and Martin Luther King Jr.

The Kennedy-King dinner at the Hilton on Seminary Road will raise an estimated $100,000, with tickets ranging from $75 per person to $2,500 for a benefactor table.

Craig K. Bieber, executive director of the state party, took a shot at Gilmore's celebratory fund-raising, which has few precedents in a state with some of the least restrictive campaign finance laws in the country.

"This just strikes me as a king traveling through his kingdom, greeted at every turn by his loyal subjects and exacting tribute," Bieber said. "It's reinforcing the idea that people have about him, that he's regal and dictatorial and demands loyalty and tribute at every turn."

The guest list tonight was a Who's Who of Virginia Republicans, including U.S. Rep. Thomas J. Bliley Jr. of Richmond, a political mentor of Gilmore's and the evening's master of ceremonies.

Todd Reid, Gilmore's principal staffer at his New Majority Project PAC, said there were at least 10 "co-chairmen" for the dinner--at $25,000 for a 10-person table--though most guests bought cheaper tickets, starting at $1,000 for two places at dinner and ranging up to $10,000 for a table for six.

The dinner menu included no dessert, because a giant birthday cake was to be laid out in the Jefferson's ornate rotunda for carving later. The governor's wife, Roxane Gilmore, was to toast her husband, who turned 50 on Wednesday.

Reid said the fund-raisers were going to surpass their original goal of $1 million for the PAC--all of it already earmarked for legislative incumbents and challengers across Virginia--and were approaching the $2 million mark.

"It's headed that way," Reid said. "We're getting close."

CAPTION: Former president George Bush, left, is greeted at a fund-raiser by Gov. James S. Gilmore III, who is using national Republicans in local campaigns.