The American voters gave George Bush and the Republican Party a pattern-breaking presidential victory yesterday but blurred the import of their decision by cautiously opting once again for divided government in Washington.

The outcome of the long and expensive struggle signaled little more than the start of a new round of political warfare, one in which the White House and Congress will wrestle for control of the policy agenda and both parties will search for answers to vexing problems -- like the budget deficit -- which the candidates sidestepped on the stump.

After a campaign in which the vitriol drowned the vision, Bush elevated the GOP to its third successive presidential victory, a feat the Republicans had not accomplished since 1928. In the process, the patrician Yankee-turned-Texan, whose political prowess had never been established in a skein of appointed jobs, became the first sitting vice president to win the top prize since Martin Van Buren in 1836. But if the voters meant that either as a personal accolade or a policy mandate, they muffled the signal by giving Democrats a renewed vote of confidence in congressional and state elections. The split verdict immediately triggered charges that Democratic nominee Michael S. Dukakis had cost his party a chance for a sweep by his political shortcomings and tactical misjudgments. The defeat of the Massachusetts governor, who led Bush by 16 percentage points last summer, is certain to renew furious internal debate about the future direction and leadership of the Democratic Party, which has lost five of the last six presidential elections.

But the evidence suggests that the preference for divided government -- with Democrats looking after domestic needs in Congress and the state capitols while Republicans manage the economy, defense and foreign policy from the White House -- may have had as much to do with the outcome as any impressions created by the often-venomous campaign. An NBC News-Wall Street Journal poll just before the election found voters by a 5-to-3 margin thought it better for different parties to control the White House and Congress. Ken Adams, 35, a tire-store owner in Clarkston, Ga., and pro-Bush Democrat, spoke for many when he said yesterday, "I'd rather have a little argument going to work things out." Echoed Karen Ekegren, 54, a Chicago office worker, "It's not good to have one party in control."

Scholars of presidential elections said they were sure that in-depth analysis of the unprecedented mass of polling data this election generated will demonstrate that peace and prosperity were the fundamental forces behind Bush's victory. Six years of sustained economic growth, low inflation and declining unemployment, coupled with improving relations between the United States and the Soviet Union, boosted President Reagan's popularity back up from its Iran-contra lows. And as Reagan's standing rose, so did support for his loyal vice president.

William Galston, a professor of public affairs at the University of Maryland and adviser to past Democratic presidential candidates, said, "All year long, the voters felt the tension between general satisfaction with the present and vague but pervasive anxiety about the future. In the end, the present trumped the future."

That left the question of mandate open to interpretation. Paul Weyrich, a leading conservative strategist, argued that "if the Democrats take the policy initiative on the basis of their projected Senate gains, they will probably get somewhere with it. They could say voters were deliberately tying Bush's hands because they were worried what he might do." Such was the case with Barbara Cleveland, 47, an interior designer, who told a Post reporter outside her Aurora, Colo., polling place that "I've just voted for a Democratic presidential candidate for the first time in my life. Bush is supposed to win and I do not want him to think he has a mandate to do whatever he wants."

"George Bush will face a very basic task of changing a political coalition to a governing coalition," agreed Reagan pollster Richard Wirthlin, "and it will be stiffer because of the nature of the campaign he ran."

Several leading Democrats gave early indications they would not quickly forgive or forget Bush's tactics against Dukakis. Sen. Bill Bradley (D-N.J.) said, "It will be very difficult for George Bush to govern, not because of divided government, but because of the way he conducted the campaign. He will be forced to ask for a tax increase, and when he does, Democrats will say, 'Read our lips." In a similar vein, House Ways and Means Committee Chairman Dan Rostenkowski (D-Ill.) told NBC News, "I don't read lips. If George Bush wants to do something about the deficit, I don't see how he can do it without putting revenues into the equation."

Not all prominent Democrats were so belligerent. Jesse L. Jackson, runner-up for the nomination, told ABC News, "I hope we get the campaign agenda behind us," and start concentrating on social programs to achieve the "kinder, gentler nation" Bush had set as his ideal in his acceptance speech. Sen. Edward M. Kennedy (D-Mass.) said, "The problems are too important for the Congress not to work with the president."

Last spring, when the primaries established Bush and Dukakis as the November opponents, Lee Atwater, Bush's manager, said that the autumn campaign would provide a "classic test of the cyclical vs. the ideological forces" in American politics. The dynamic of the 1988 general election can perhaps be best understood in terms of those rival forces of cyclical forces and ideology.

During much of the spring and early summer, Dukakis -- with 10 years' experience as an innovative governor but a newcomer to the national stage -- presented himself largely as an agent of change. He was the man who would end unpopular foreign engagements in places like Nicaragua, prudently prune Pentagon spending and redirect resources toward such popular domestic goals as improved health insurance and easier access to housing and college -- all in cooperation with business and without higher taxes. On that basis, Dukakis hoped to persuade voters to make a change in the White House after eight years of Republican control.

In the two conventions last summer, the balance began to shift slowly in Bush's favor. Dukakis strengthened the moderate image he first acquired by running against Jackson by choosing a Tory Texas Democrat, Sen. Lloyd Bentsen, as his running-mate. Bentsen proved to be a far more adept campaigner than his previous history had indicated -- and the most popular man on either ticket. But in Electoral College terms, as yesterday's returns indicated, the gamble did not pay off. Despite Bentsen, Dukakis was overwhelmingly defeated by Bush in the battle for Texas' 29 electoral votes.

The Democratic convention also required Dukakis, for the first time, to confront Jackson, the dynamic black leader whose policy views more than fulfilled Republican descriptions of Democrats as the party of the Left. Their negotiations -- and Jackson's fiery convention speech -- dominated all but the last day of television coverage from Atlanta. As scores of voter interviews later evidenced, many of those watching decided -- despite the denials by both men -- that some secret deal had been struck.

Starting with the Republican convention in August, Bush developed the two-pronged strategy that produced yesterday's victory. On its opening night, Reagan gave a valedictory speech in which he proclaimed, "We are the change," and Bush picked up the cue. He appeared a new man personally -- liberated from the self-endorsed servility of the vice presidency and delivering a confident, tough, occasionally uplifting acceptance speech which dazzled even the previously derisive Democrats.

And while he was seeking to blunt the cyclical forces aiding Dukakis, he orchestrated a strident attack on Dukakis' credentials intended to paint the governor as a permissive liberal who showed little respect for the flag and undue concern for the welfare of criminals.

The potential of this twin offensive was obscured for a time by the controversy over Bush's surprise selection of Sen. Dan Quayle of Indiana as his running mate. Bush used the furor to demonstrate his own firmness under fire. "His knees did not buckle," observed former Republican National Chairman Bill Brock. Equally important, after demonstrating his tenacity, Bush tacitly acknowledged his error of judgment and banished Quayle to the political boondocks with a crew of Bush-chosen managers riding posse to keep him as much as possible out of voters' sight.

By Labor Day, the anti-Dukakis ads had begun to take their toll, painting the Democratic nominee into the "liberal" corner and pounding home the message that "America can't afford that risk." Dukakis' failure to fight back -- either in ads or in the two televised debates -- dismayed many Democrats.

Greg Markus of the University of Michigan, one of several academics who predicted the outcome months in advance based on factors like changes in real income and levels of presidential approval and the absence of serious intra-party conflict among Republicans, said, "Any GOP presidential nominee in 1988 would have had to work awfully hard to lose the election."

But Paul Maslin, a Democratic pollster and consultant, had company among party activists for his judgment that "the American people wanted change -- and still do. I don't buy that the loss was inevitable."

Maslin and former Arizona governor Bruce Babbitt, an early contender for the Democratic nomination, said the outcome highlighted the failure of Dukakis -- and the Democrats generally -- to define themselves clearly on the overriding issues of peace and prosperity. "This is not a technical problem," Babbitt said. "It is not a competency problem. Maybe none of us could have won, because our failure was to articulate a large vision about the economy and the world. In a vacuum, these picayune issues like Bush raised, these symbols, become important."

"It all comes back to the nominating process," said Sen. Terry Sanford (D-N.C.), a veteran of past efforts at internal party reform. "We have a system where you fight your way up on your own . . . and that makes it hard for these people to realize they have to reach out for help from other Democrats. That was the mistake the Dukakis team made."

While Sanford worried about the nominating process, others in both parties worried about the precedent that was set by the seeming success of strong negative ads, launched by the Bush campaign and belatedly answered by Dukakis. "I'm afraid these campaigns are here to stay," said former Reagan manager Rollins. "The one arena they hadn't been tried before was the presidential race, and now we've seen that they work even there."

Political researcher Colette T. Rhoney, staff writer Morris Thompson and special correspondents Susan Kelleher and Lauren Ina contributed to this report.