Gov. Michael S. Dukakis and the Reverend Jesse L. Jackson are running a tight race in Wisconsin, while neither Sen. Paul Simon (D.-Ill.) or Sen. Albert A. Gore, Jr. '69 (D.-Tenn.) are serious threats in today's crucial primary contest, poltical analysts and campaign workers said yesterday.

"It's a dead heat, it's a flip of the coin," said Bob Burns, a spokesman for the Jackson campaign in Milwaukee.

"We're in pretty good shape," said Tony Tsakakis, spokesman for the Dukakis campaign in Milwaukee. He said the latest polls show Dukakis with a slim but significant lead with 43 percent support to Jackson's 35 percent.

The recent withdrawal of Rep. Richard Gephardt (D.-Mo.) has left a small pool of uncommitted support which both Jackson and Dukakis seem to be dividing evenly, the experts said.

Following Jackson's stunning triumph in the Michigan caucuses, the Wisconsin primary has taken on large importance in the campaign. A Jackson victory could well propel him to the nomination, while a Dukakis triumph could stem what seems to be a growing Jackson groundswell.

"No one thought he was more than a blip on a screen until Michigan," said Boston political consultant Michael Goldman of Jackson. "Now Democrats are getting seriously worried." Victory today would mean that Jackson may win the Democratic nomination but he would meet certain defeat in the general election, Goldman said.

But since Wisconsin has a very small Black population, Jackson's main voting base, a strong showing would add credence to his claim that he is capable of drawing support from all voters.

Burns said that Jackson and Duka- kis are campaigning in the same places and forthe same voters.

Goldman said that the lack of competition onthe Republican side of tomorrow's primary maycomplicate things for the Democrats, andespecially for Dukakis.

Some Republican voters are expected tocrossover and vote for Jackson under Wisconsin'sopen primary system in an attempt to undermine theDemocratic effort in November, Goldman said. Thesabotage effort is premised on the belief thatJackson is too left-wing to win a nationalelection, he said.

Recent polls show that a Dukakis/Jackson ticketwould beat Bush in the national election, saidDavid Runkel, Deputy Director of the KennedySchool's Institute of Politics. Although he hadnot seen the numbers, Runkel said the pollconfirmed his view that "Jackson is a factor in'88, on the ticket or off."

While Bush has not yet won the necessary numberof delegates to officially declare himself theRepublican nominee, he is well on his way.

With his main competitor, Kansas Senator RobertDole, now out of the race, Bush is focusing on thenational race, a spokesman for the Bush campaignin Milwaukee said yesterday