Washington — As the US economic recovery picks up steam, the Democrats are realizing they will have to attack the Reagan Republicans on a broader front than recession alone.
The economy alone won't do it for the Democrats in 1984, party strategists warn. They cannot run a passive election campaign. And the Democrat who stands out from the pack to win the nomination will have to appeal to the party's liberal instincts on noneconomic issues - particularly among youth, who are seen by some as the leading edge of future party success. Nuclear arms, the environment, and social issues like abortion may offer the vivid issues needed to thrust a nominee ahead of the crowd.
The problems the party faces in trying to attract young voters is indicative of its campaign problems generally. Democrats acknowledge they need to inspire voters if they're to compete against an economy-on-the-upturn Republican candidate.
The Democratic Party ''needs to get out of its complacency, thinking we can benefit from anti-Reagan sentiments,'' says Chris Knowles, a young financial analyst from Des Moines and a member of the Iowa Democratic central committee. ''Had the economy continued as it went in 1982, any viable Democratic candidate could have made a real run at Ronald Reagan. But things do not look as bad today as they did 90 days ago.''
Mr. Knowles's comments typify his generation's search for a candidate that prompts positive reasons to vote for him. He mentions the environment, training more math teachers, foreign-language training, nuclear arms control, and social programs as high on his list.
''I want to maintain a strong defense,'' Knowles says, ''but I'm not for as strong offense as the Reagan administration seems to want. Arms - nuclear nonproliferation or control - is probably the single most important issue for 1984, if not the one that decides the election.
''I've got a seven-year-old son. I at least want him to become as old as I am. The current nuclear threat casts a pall over people, particularly over young people.''
Democratic professionals warn that their candidates are letting President Reagan define their position for them, a little left of center. So far, they say , the candidates are offering the public little emotional reason to vote for them.
''The candidate who can succeed in November 1984 will be the one . . . who can convince people on other issues (apart from the economy) that there is a difference between our party and their party,'' says Paul Maslin, vice-president of Cambridge Research Associates, a Democratic polling firm.
Democrats as yet see no galvanizing issue like Vietnam riveting youth's attention. But the Environmental Protection Agency inquiry now cooking in Washington and the El Salvador aid issue are events that could ignite strong political fires.
''The candidate who succeeds will have to provide the spark to light that fire,'' Mr. Maslin says. ''That underlines the importance of young voters.''
He asserts that Democrats don't have the backing of young people on economic issues. ''It is older people who are more negative to Reagan on the economy.
''It was the baby-boom group - the noncollege-educated, not just college youth - that was the biggest swing group from 1976 to 1980. Blue-collar, high-school grads were typical of American people for whom the American dream had started to fade. That's the group that really started to move to Reagan in 1980 - the 25- to 35- or 40-year-old age group - in big numbers.''
This younger block of voters began to swing back to the Democratic Party last November. But they're still up for grabs.
Each presidential campaign competes for a new and larger youth group, a new generation of campus graduates. In 1972, for example, there were some 9.2 million youths on campus.
There are now 12.4 million. This compares with 2.3 million in 1950, and 4.8 million in 1963. Democrats will have to campaign on campuses again in '84, in a way they haven't since 1972, when the Vietnam war issue turned them out in droves.
They will have to court campus youth for defensive reasons: A third-party candidate like a John Anderson could siphon off crucial voters who would not vote for Reagan but would vote for the Democratic nominee if there were not an independent candidate.
''Walter Mondale is lackluster,'' says Knowles, who admits he is still shopping for a nominee to support for the campaign. ''He is the Democratic establishment candidate, no doubt about it. He has the best resume if you were to hire a president. He has ability. He's conducted himself well as senator and vice-president. He's the heir apparent to the out-of-power party.
''We do not have a Vietnam; there's no overhanging youth issue,'' says Maslin. ''There are the makings for some issues, however. And it will also take some events helping out. It can't just come out of a campaign.
''Specifically those issues are: first, the whole nuclear arms question; second, the environmental/nuclear-power/general-quality-of-life question in the country; and third, the social issues such as abortion. . . .
''If anyone could blend those issues together - or two out of the three - and events occur to heighten their impact, there's a huge voting bloc out there waiting to participate.''
Democrats did well last November in almost all the big states among the 35 -and-younger age groups, Maslin says. Black youths, too, are increasingly active. In the recent Chicago primary and in Northern and Southern states that held black registration drives in 1982, it was younger blacks, primarily under 30 years old - well targeted by the drives' directors - who made the difference in key races.
Blacks, impatient with mainstream party coalition tactics, are threatening to field their own presidential candidate. It might take bold steps - starting with a commitment from front-runner Walter F. Mondale or others to hold the 1984 Democratic convention in Chicago, where black mayoral candidate Harold Washington will likely win office in April - to keep restive blacks in the party.
Democrats are doing better with women. President Reagan's slight approval rating gains since the recovery began in January have been mostly among men. His gender gap - a greater unwillingness among women to support him - persists. But even here, Democrats will have to move forthrightly to turn out women voters.