ORLANDO, FLA., NOV. 14 -- The national struggle pitting the establishment wing of the GOP against evangelicals pouring out of Assembly of God churches came to a head in Florida today with Vice President Bush winning a hard-fought victory over Marion G. (Pat) Robertson in a straw poll of Republican activists meeting here.

Bush was the clear winner with 1,322 of 2,313 votes, 57 percent, and Robertson well behind with 849 votes, 37 percent. But the numbers hid the organizing strength of the Robertson campaign, which bucked a voting system clearly set in place to provide a massive edge to the candidate with the backing of the party leadership, like the vice president.

Robertson's votes indicated that he had gone head-to-head with Bush among the 1,438 delegates selected through an open caucus process and won in that arena. The remaining delegates were selected by the party leadership, dominated by Bush supporters, or they were automatic delegates because they hold elected office or had made large contributions to the state party.

Nevertheless, for Robertson, the Florida results were nowhere near as successful as caucus and straw poll battles he fought with Bush in Iowa and Michigan, where he has defeated the vice president.

Although the straw poll has no direct effect on the selection of 88 Florida delegates to the national GOP convention, Bush and Robertson each invested hundreds of thousands of dollars in a seven-month battle to line up delegates to this event, known as Presidency II.

With banners, command centers, balloons, posters and straw hats, and with key operatives armed with walkie-talkies and color-coded computer lists of delegates, the Florida contest took on all the trappings of a mini-national convention. It had, however, the unreal quality of an expensive movie set, as all four other Republican presidential candidates opted out of the contest, most of them complaining that the rules were "rigged" to favor Bush.

There was token support of about 3 percent for Rep. Jack Kemp (R-N.Y.), and one percent or less for former secretary of state Alexander M. Haig Jr., Pierre S. (Pete) du Pont IV and Senate Minority Leader Robert J. Dole (Kan.). Dole's votes were not announced because he had withdrawn his name from the ballot.

The results contrast sharply with public opinion polls of the state. The most recent Mason-Dixon Poll here gave Bush 43 percent, Dole 24 percent, Robertson 9 percent and the rest less, and all polls show Robertson's negative ratings substantially higher than favorability ratings.

While the outcome of the Florida straw poll may have little significance, it became a microcosm of the divisive cultural battle taking place within the GOP across the nation. On one side are traditional Republican leaders and activists; on the other is the growing army of white, Christian evangelicals that has provided the single largest source of new blood for the party in the last decade.

This conflict reached its most intense moment here Friday night when 1,500 Robertson delegates, supporters and their relatives left a rally at the civic center to form a massive, chanting chain -- a conga line of fervor. The line marched across the street to the plush Peabody Hotel to weave through the network of bars and lounges shouting "We Want Pat; We Want Pat," as disgruntled Bush delegates watched uncomfortably, sipping martinis, scotches and beer.

"Everyone I know that is a Robertson supporter is a zealot. We are committed," said the Rev. Ronald Johnson, pastor of the Wekiva Assembly of God Church in Longwood, Fla., and a Robertson delegate. "When the flag goes up, Robertson's people stand up," said the Rev. John Wisner, an Assembly of God pastor and Robertson convention floor whip.

Bush and Robertson both addressed the convention. While each stressed conservative themes, they diverged in the tone and content of their crowd-pleasing lines -- Bush pressing his credentials as a tough anticommunist, Robertson hitting social issues with a harder edge than usual.

At the start of his speech, Robertson declared: "I have no intention of giving the streets of America over to the radical homosexuals," a group he blamed for disrupting the formal announcement of his presidential bid last month in New York. He contended that studies show the nation's welfare system causes 30 percent of all divorces, and attacked the legal services program for providing counsel in 225,000 divorce cases.

"As president," he said, he would "once again bring God back into the classrooms of America," a pledge that brought his partisans to their feet to shout their approval.

Bush was introduced by his son, Jeb, who quoted Marine Lt. Col. Oliver L. North, a "great American patriot," as saying that the vice president's "actions were some of the bravest that I've seen from anybody."

To an audience of delegates that included many intensely anticommunist Cuban Americans, Bush then declared: "As president, I will never leave the contras twisting in the wind . . . . I don't care what the liberals say, as president I will strengthen the CIA, and not weaken it."

Bush sought to capitalize on his loyalty to President Reagan, who remains quite popular among Republicans here, affirming that "If the price of the top of the ladder is to shove the president down a notch, to jump away when the going gets tough, I am not willing to pay that price."