For the first time in a national Gallup survey, Democrat Michael Dukakis has taken the lead over Republican George Bush in a test of strength for the presidential election this fall. Voters nationally now prefer Dukakis over Bush by a substantial margin of 54 percent to 38 percent. Our last survey _ taken before the Massachusetts governor's string of Democratic primary victories in Pennsylvania, Ohio, Indiana, West Virginia and Nebraska _ showed the two men dead even (Bush 45 percent; Dukakis 43 percent) in a similar test election.

Now enjoying a seven-to-two advantage over Rev. Jesse Jackson (69 percent vs. 21 percent) in preferences for his party's nomination among Democratic voters and Independent voters who lean Democratic, Dukakis is uniting his party.

He runs strongly against the GOP vice president among all of the traditionally Democratic constituencies and is even picking up some defections from Republican voter groups that had been very solid Reagan-Bush supporters. With his political fortunes so closely tied to Ronald Reagan's, George Bush is clearly suffering some ill effects from the spate of negative press coverage _ astrology, Ed Meese, Noreiga, etc. _ the White House has been receiving lately.

Since early March, the proportion who approve of the way Ronald Reagan is handling his job has decreased from 52 percent to 46 percent. Moreover, the proportion who disapprove of Reagan's performance (42 percent) is now about equal to the proportion who approve (46 percent).

Patterns of Support in a Bush vs. Dukakis Race.

Since a national Gallup survey in April, Dukakis has gained on Bush among virtually all voter subgroups. His gains are particularly noteworthy, however, among blacks, young people, residents of Western states and well-educated Republicans.

One month ago, in the aftermath of the contentious New York Democratic primary, nearly one in five black Democratic voters (18 percent) indicated a preference for Bush if Dukakis, rather than Jackson, were Bush's fall opponent. That proportion has since decreased to 10 percent. Fully 85 percent of black Democrats and Democratic leaners now support Dukakis in a race against Bush. This brings the black Democratic constituency in line with the party's other two major voter blocs. Ninety-two percent of white New Democrats (under 50 with some college training) and 80 percent of white Traditional Democrats (50 and older, no college) prefer Dukakis over Bush.

Reagan and the Republican Party generally received higher-than-average ratings among young people during the Reagan years. Consistent with this tendency, the only age group among whom Bush had an advantage over Dukakis one month ago was voters under 30. In the current survey, Bush has lost his advantage among younger voters _ they now prefer Dukakis by 57 percent to 40 percent.

As the Democratic primary campaign has moved into California, preferences among voters in Western states have changed to a 54 percent to 38 percent Dukakis advantage over Bush; Dukakis had trailed the vice president by 37 percent to 52 percent in the West last month.

Dukakis has even been able to make significant gains at Bush's expense among a group that would seem to be Bush's natural constituency _ college educated, non-evangelical Republicans. One in five (21 percent) of these voters, who tend to espouse an economically based brand of Republicanism, now support Dukakis in a test election against Bush. Only 8 percent of this group backed the Democratic front-runner in the April survey.

Strength of Support and the Anti-Vote

As seen in primary races, neither Dukakis nor Bush attracts the kind of strong support that is associated with a candidate like Jackson. Only a third of all voters now strongly support either man, indicating that there is a great deal of potential for shifts in voter sentiment between now and November.

It should be noted, however, that Dukakis now has a slight advantage over Bush (19 percent vs. 14 percent) in total "strong" support. As seen in previous surveys, voters continue to say they are making their choice more on the basis of how they feel about Bush than on the basis of how they feel about Dukakis. On this measure, however, things are also going Dukakis' way. The proportion of voters who say their choice is basically a pro-Dukakis vote now about equals the pro-Bush vote (26 percent vs. 27 percent).

And, while a sizable proportion of voters describe their preference in a Bush-Dukakis race as an anti-Bush vote (25 percent), few call themselves anti-Dukakis voters (7 percent).

Bush vs. Dukakis

Mar. Apr. May

10-12 21-23 13-15

PCT PCT PCT

Bush 52 45 38

Dukakis 40 43 54

Other/

Undecided 8 12 8

Total: (625) (1,204) (1,204)