THE PRINTED invitation to the Paul Simon fundraiser in Washington last month ended with this breathless bit of marketing: "Ranked 2nd of 7 Democrats . . . ABC News Poll."

Left unwritten, of course, was that Sen. Simon was the choice of only 13 percent of the Democrats surveyed, nine points behind the Rev. Jesse Jackson. And, oh yes, Simon technically was tied for second with Gov. Michael Dukakis and "No Opinion," that traditional early-season spoiler.

But ignore those quantitative quibbles. Enjoy: As entertainment, these early polls may have modest value. As predictors of the eventual Democratic winner, however, the pre-season polls are failures.

It's almost a tradition that early Democratic preference surveys are led by losers. Ed Muskie, Hubert Humphrey and Ted Kennedy all topped the polls a year before the party convention, only to collapse. This year's early front-runner, Gary Hart, is gone. Now Jackson is sinking fast. For a superstitious Democrat, the safe strategy might be to conceal rather than advertise an early lead.

Yet among Republicans, there's been only one true flop in the past 30 years: Nelson A. Rockefeller led the early presidential polls in 1964; Barry Goldwater won the nomination.

Pollsters generally agree that the leader-to-loser phenomenon reflects the simple fact that early candidate preference is based largely on name recognition. Commitments to individual candidates can be shallow. Voters really don't begin paying attention to presidential politics until the first primaries.

So why, then, do Republicans generally stick with early front-runners and Democrats often come unstuck? Theories abound. Here are some of the most popular:

The fresh-face factor. Some political observers argue that Democrats are more susceptible to late-blooming candidates. Others claimthat Democrats are merely crueler to front-runners. "Recent political history," writes Andrew Kohut, president of the Gallup Organization, "indicates that fresh faces have more appeal to Democratic voters than to Republicans, who tend to stick with front-runners to a greater degree."

Party demographics. The Democratic party traditionally has been more of a demographic and ideological salad bowl than the GOP. That means a Democrat has had to build a lead from poorly fitting and often competing voter blocs -- urban blacks and ethnic whites, for example. The result may be inherently unstable. "Democrats have just been more pluralistic," says California pollster Mervin Field. "What it gets down to is that the Democratic party seems to have room for a much wider range of political voices, and have the ability to segment and fragment more. Take the 1972 race having Scoop Jackson in there with George McGovern. You rarely see that kind of range among Republicans."

The info gap. Republicans know more about their candidates, and know it earlier. "Republican voters generally are more informed about most things, including their political candidates, than are Democrats," Kohut said in a recent interview. "Democratic voters are more likely in pre-primary polls to be reacting only to name recognition, and therefore are a little more likely to desert the front-runner."

Early-cash syndrome. Republicans are handier with a buck. GOP fundraisers are notoriously more adept at milking party cash cows than are Democrats. This gives early leaders a quick-strike capability to dry up available money before the first primaries, leaving little for fresh faces. Democratic dollars remain parked on the sidelines longer. Relatively unknown Democrats can bet everything on the first Democratic primaries. They know late money is available, the theory goes, but only if they finish strong.

Different primary strategies. Each party plays by different rules. Field suspects that reforms in the way Democrats select delegates may have helped the chances of party unknowns. GOP primary rules may be less overtly democratic and more favorable to established party stars. Others have suggested this result: An informal order of Republican succession in which one candidate is understood early to be the heir-apparent. "What you have had on the Republican side," says Field, "is the so-called logical candidates emerging. Eisenhower the hero, Richard Nixon, a two-term vice president, then Ford who had been vice president, were candidates like this."

Still, the early polls are far from useless to Democrat-watchers. They are particularly helpful to an aspiring fresh face who must demonstrate to party insiders that they have national appeal. A first- or second-place finish isn't essential. But name-recognition and numerical evidence of a potential national constituency are mandatory.

Once established, the rewards of legitimacy can be great. They take the form of invitations to feed at the cash trough of political patrons like Stewart Mott, the Washington money-man who hosted the Simon fundraiser last month. Other benefits include the enhanced ability to attract top talent to run a national campaign, and party activists to staff it.

Political scientist Michael Hawthorne says presidential campaigns move in clear phases. Candidates first work out of public view to build a campaign organization. At that point, a commitment from a proven fundraiser can be worth more than a bump up in the national polls. "We've been out of that stage for several months," Hawthorne said. "The second phase is when the campaign starts to go out to the activists, away from the very biggest contributors to a broader base of people who may contribute several hundred dollars rather than tens of thousands, and who are also campaign workers."

That's precisely what Simon was attempting to do last month. His candidacy has played well to the political literati in Washington. Now he must prove that his bow tie and big ideas work as well beyond the Potomac. And he must prove it before one of the other Democratic dwarves becomes the fresh face of 1988.

Richard Morin is The Washington Post's director of polling.