Will Democratic `unity' mean winning margin?

Dukakis-Jackson amity has sent hopes soaring here at the Democratic National Convention. After days of squabbling, Michael Dukakis and his major rival, Jesse Jackson, patched up their relationship Monday, and simultaneously struck a major blow for Democratic prospects this fall.

The sudden reconciliation was a surprise in a city braced for a Dukakis-Jackson showdown later this week. It was also a setback for the Republicans.

``Republicans have always banked on a disruptive Jesse Jackson to strengthen their hands for the fall campaign,'' said political scientist Thomas Mann of the Brookings Institution. Perhaps most important, Governor Dukakis appeared to bring the Rev. Mr. Jackson onto his side without giving too much away.

Early indications were that Dukakis yielded very little. He announced that the two campaigns would be ``integrating our organizations,'' bringing some of Jackson's campaign workers onto his staff.

He promised that Jackson would play a major role in the fall race, that they would ``campaign together'' at times.

There was also a commitment, according to Jackson, that the campaign would emphasize Jackson's issues: plant-closing legislation; statehood for the District of Columbia; universal, same-day voter registration; anti-apartheid legislation; child care provisions; and economic development programs. But during a joint appearance here, there was no mention of the ``partnership'' that Jackson had demanded in earlier statements.

Politically, the most important part of the Dukakis-Jackson rapprochement was that the party now has the opportunity to fly with two strong wings.

Jackson will be working to rally the liberal wing behind Dukakis, especially blacks and Hispanics who have supported him so strongly. At the same time, Sen. Lloyd Bentsen of Texas, the vice-presidential choice, will give Dukakis an opportunity to attract large numbers of voters from the disenchanted conservative wing of the party, including both white Southerners and Northern, Roman Catholic ethnic voters who have deserted the Democratic Party during the past two national elections.

Some disputes between Jackson and Dukakis could still add a few lively moments to the four-day convention that ends Thursday. Tonight, for example, Jackson still may push for several platform planks on defense, tax, and children's issues. But he rejected proposals by some supporters that he be nominated for vice-president against Mr. Bentsen.

Analysts quickly assessed the impact of a unified party. Jackson's strong support could help Dukakis in states where the black vote is large, and could provide the winning margin in a close race.

That might include states like Pennsylvania, New Jersey, and Connecticut in the Northeast; Ohio, Michigan, and Illinois in the Midwest; Tennessee and Arkansas in the South; and California in the West.