Dallas — President Reagan, who steps forward tonight to accept his party's renomination, can expect a hard-fought campaign that analysts say will probably end much closer than it is now.
''This is going to be a fighting election'' highlighted by ''drama and conflict,'' says political analyst James David Barber.
Even top-ranking GOP planners say the polls, which give the Republican ticket a lead of 10 to 15 percent, are almost certain to get tighter. They are amazed that the Reagan lead has been so strong and lasted so long.
How strong is Mr. Reagan? Surveys show him ahead in unexpected places such as Maryland and Massachusetts. He's currently only 2 points behind the Democrats in Walter Mondale's own Minnesota.
The big Reagan lead, and his position as an incumbent, will go a long way toward shaping strategy in both the Reagan and Mondale camps in the days ahead. A number of analysts say the battle plan each party should follow is fairly obvious.
The GOP theme should be ''Reagan, Reagan, Reagan.'' It should focus on the President, on his achievements, on his personal popularity.
The Democrats' theme should be ''Republican, Republican, Republican.'' In that way, they can make the election more partisan, rally Democrats (who are more numerous), and call attention to what many analysts feel is Mr. Mondale's most powerful argument - the so-called fairness issue, also known as ''Reagan and his rich friends.''
The President will not sit on his lead, says campaign manager Ed Rollins. Nothing will be taken for granted. Another Reagan planner, Lyn Nofziger, says far more campaigning is being mapped out for the President now than was expected only a few months ago.
One reason is the unknown impact of Geraldine Ferraro on the Democratic ticket. Despite all of Ms. Ferraro's difficulties over financial disclosures, Republicans remain uncertain whether she will be a big plus or a minus for the Mondale campaign. In this uncertain atmosphere, the GOP wants to take no chances.
Despite a busier schedule planned for the President, there are indications that GOP campaign officials are being careful to keep President Reagan in structured, formal events - rather than spontaneous, unrehearsed ones.
Says one analyst outside the campaign: ''Reagan's people will try for tight control. They'll give him a script ... and he'll deliver the lines. The one way that he could lose this election is that he suddenly, in some casual comment, goes off on the wild blue yonder,'' such as his recent joke, off the record but into a ''live'' microphone, about bombing Russia.
Mondale, to have any prospect of victory, will be forced down another path. He must take chances. He must push hard. He must look for spontaneous breakthroughs - which his staff hopes will come in a series of debates that Mondale has called for with Reagan.
Hanging over the whole Mondale campaign, of course, is the uncertainty about Ferraro. Packs of investigative journalists have been digging into her financial background and that of her husband, real estate businessman John Zaccaro. Whether this week's press conference by Ferraro and her release of several years of the Zaccaro and Ferraro tax returns will be enough to satisfy the press remains to be seen.
If the issue is still burning after Labor Day, it could be devastating to Democratic hopes.
When the Republican and Democratic campaign planes lift off on Labor Day for the final phase of this campaign, what kind of race can be expected? Some experts put this year in the same category as 1956, when Dwight D. Eisenhower ran for reelection.
Stephen Hess of the Brookings Institution, a former speech writer for Eisenhower, says that what this election is really all about is ''thumbs up or thumbs down'' on the Reagan presidency. If people like what Reagan has done, he'll be returned. If not, he'll be turned out. That's the major factor - really the only important factor - this year, Mr. Hess says.
Reinforcing the comparison to 1956 has been the upbeat, confident mood of this Republican convention in Dallas. This has been the smoothest, most harmonious gathering of the GOP since the Eisenhower years in the '50s. That was an era when the country enjoyed both peace and abundant prosperity - a time that later inspired the popular TV show ''Happy Days.'' In 1956, ''Ike'' won reelection in a landslide.
Others, including Dr. Barber, agree with the premise that this will be a vote for or against the Reagan record. But they suggest that 1984 will look more like 1948, which turned into a highly partisan clash.
Mondale, in fact, has been encouraging comparisons with '48, when Harry S. Truman came from far back in the polls to upset Gov. Thomas E. Dewey of New York , the Republican nominee, in a wild, partisan fray.
The evidence that we're about to have a bare-knuckles campaign is already there, suggests Barber. Even before the usual Labor Day start, both major party candidates are on the trail blasting each others' records.
Barber also bases his outlook for the coming campaign on his own theory of political cycles in US presidential races.
His theory, spelled out in his book ''The Pulse of Politics,'' has caused some controversy. But even some of his critics say Barber's theory helps to analyze the dynamics of elections.
Comparing White House elections over several decades, Barber contends that the country goes through predictable, 12-year cycles in its elections. A combative campaign, such as Truman-Dewey, tends to be followed a ''moral crusade'' - as the first Eisenhower-Stevenson election. That, in turn, is succeeded by one that seeks to pull the country together, to conciliate.
Then the cycles repeat - conflict, morality, conciliation.
The Carter-Ford election came in the year (1976) that Barber's theory would have predicted an campaign calling for greater morality in government. That election, one will recall, came just after Watergate.
The Carter-Reagan contest (1980) occurred in a conciliation year, according to the Barber cycle. One can recall Republicans at their convention waving the American flag, and calling for ''A New Beginning.''
This theory is considered ''a little too neat'' by some critics.
Barber readily concedes you can find similar elements in every election, but he contends that American politics does seem to go through cycles similar to the ones he tried to map.
What this means for 1984, suggests Barber, is that morality won't get the high-profile attention it did when Jimmy Carter first ran.
Nor will patriotism be as effective a political device as in 1980. Each tactic has been used recently.
This year, Barber expects old-fashioned partisan clashes - ''slam bang'' campaigning.
That can be good or bad, he says. If it degenerates into mudslinging, little will be gained. If, on the other hand, it results in a deeper investigation of the issues, everyone could benefit.