Less oomph in Dukakis `bounce'. His 17-point lead over Bush shrinks to seven in Gallup poll

George Bush, after two weeks on the attack, is gaining ground on Michael Dukakis. The latest Gallup poll shows Governor Dukakis's lead whittled down to only seven points, well below the 17-point margin he enjoyed after the Democratic National Convention.

Susan Estrich, Mr. Dukakis's campaign manager, concedes that the polls could be dead even in another week, after the Republican convention in New Orleans.

``We've been saying ... that this race will tighten up,'' Ms. Estrich says. She observes that when Vice-President Bush fell to only 33 percent in one recent poll, that was unrealistic.

Mr. Bush has gotten a boost from three factors.

A short-lived tempest blew up last week concerning Dukakis's medical records, especially over whether he ever had treatment for mental depression. The rumor, which turned out to be false, lasted only a few days, but probably fostered public doubts about Dukakis, Estrich says.

Meanwhile, the euphoria that followed the Democratic National Convention has worn off.

Candidates usually get a ``bounce'' in the polls after their conventions - but it's good for only a week or two.

Finally, Bush has hammered Dukakis for the past two weeks as a taxing, spending liberal who is weak on defense and crime. Dukakis complains it is negative campaigning, but the public appears to be listening. It may be working with voters who traditionally line up with the GOP.

Larry Hugick, an analyst at the Gallup Organization, says that in recent days many independent voters have moved back to Bush - particularly women in their 30s and 40s who have household incomes of more than $30,000 a year.

It was those women, especially Protestants who live in the Northeast and along the West Coast, who switched to Dukakis during the Democratic convention. Now, as the excitement of Atlanta wears off, they are drifting back to Bush.

The battle for those independent voters will be critical in 1988, and it is far from over.

Mr. Hugick notes that the group, which includes many college graduates, aligns with the Democratic Party on social issues. Ordinarily, they might feel more at home with the Democrats. But they worry that Democrats cannot be trusted to hold down inflation and spending. If Dukakis can win their trust, he might win them back.

Estrich, who breakfasted with reporters yesterday in Washington, says the Dukakis campaign recognizes the importance of the ``trust'' factor.

In 1984, she says, the public was closer to Walter Mondale on many issues than to Ronald Reagan, but many voters backed the President anyway. The key to their vote was their personal trust in Mr. Reagan.

Dukakis hopes to deal with that by presenting himself as tough-minded and independent, she says. The coming presidential debates will be a perfect opportunity to do that, she suggests.

Dukakis also is striving to preempt a Republican advantage in defense and arms control. Today he visits Fort Dix, N.J., for a defense speech. Earlier, he praised Reagan's role in arms control.

Where possible, Dukakis will steer foreign policy debate toward areas where he has an advantage according to polls, such as international drug trafficking and world economic competition.

Estrich observes that eight years ago, the US was perceived to be behind in military strength. That has been corrected. Now the public is worried about US weakness in the world economic arena.

When the issue was defense, Democrats were at a disadvantage. Split since Vietnam on defense issues, the party had trouble supporting the 1980s arms buildup, even though the public wanted it. The split helped the GOP politically.

Democrats have no such inhibitions in the economic area. Democratic candidates can support measures aimed at helping the country compete internationally - such as unfair-trade strictures and expanded programs of education - without offending the liberal wing of the party.