Testing campaign themes in New Jersey

New Jersey has not been a good state for Democratic presidential aspirants. Even though Democrats outnumber Republicans, GOP tickets have carried this state in all but two elections since 1952.

But observers from both parties admit the race between Reagan-Bush and Mondale-Ferraro could be more interesting this year. And as a Northeastern state that ranks ninth in electoral votes, New Jersey is seen by many as a pivotal area. A high turnout of black voters, who came out in record numbers during the Democratic primary, and an emphasis on environmental issues could boost Walter Mondale's stock in November.

All this is not lost on President Reagan. Amid signs such as ''Welcome Mr. President, From Loretta and Joey'' and ''Reagan 4 President,'' Mr. Reagan whisked through this demographically appealing city last week, seeking to strengthen ties with blue-collar, ethnic voters who like his conservative, traditional interpretation of American life.

''He's for a strong America,'' said a man whose family held flags as they waited for the presidential limousine to pass after Reagan finished a spaghetti dinner at nearby St. Ann's Catholic Church.

''We are not looking for an easy race,'' says Bo Sullivan, vice-chairman of the Reagan-Bush '84 campaign in New Jersey. But then he ticks off issues that are favorable for the President - the inflation rate is down; disposable income is up; Reagan takes a hard-line position on crime. On national defense, voters have a choice between Mr. Mondale, who wants a verifiable nuclear-weapons freeze , and the President, who wants to work for arms reduction from a position of equality or strength, Mr. Sullivan says.

''That, to me, is more preferable. ... We have a couple of 'verifiable' [ strategic arms limitation] treaties that have been violated.''

Several observers point to New Jersey polls showing that the issues of the environment, education, and the nuclear-freeze proposal are more important here than pocketbook issues.

New Jersey has the highest number of federal Superfund toxic-waste cleanup sites. And although both Republican and Democratic politicians - such as Gov. Thomas H. Kean (R), US Rep. James J. Florio (D), and US Sen. Bill Bradley (D) - offer strong leadership on the issue, many voters perceive President Reagan as weak on the environment, says Tom O'Neill, editor of the New Jersey Reporter magazine. The controversies over former Reagan appointees James Watt and Anne Gorsuch always make front-page news here, adds an aide to US Sen. Frank R. Lautenberg (D).

This concern was reflected by some in the Hoboken crowd who watched Reagan ride down Sixth Street last Thursday. Though the President was courting Catholic and ethnic voters here, Hoboken is also home for an increasing number of young professionals who work in New York City, just across the Hudson. Although this is a group that Reagan also hopes to capture, a smattering of ''yuppies'' (young urban professionals) held signs that scored his stance on the environment and military spending.

New Jersey Democrats hope that such issues, along with an increased number of black voters, will tip the scale toward their party. And the vice-presidential candidacy of Geraldine Ferraro may also draw support.

''The question is whether [Newark Mayor] Ken Gibson and [Jesse] Jackson's people throw their support behind Mondale,'' editor O'Neill says. If the black primary turnout can be duplicated, Mondale has a chance, he says.

The Democrats lost by more than 400,000 votes in 1980, and some think there is little Mondale can do to make up that margin.

''It's not that every vote counts,'' says Jerry McCann, the Democratic mayor of Jersey City, who endorsed Ronald Reagan in 1980. What is important is who wins the popular vote in New Jersey - whether by one vote or many thousands - and thus gets the state's electoral votes.

Mr. McCann, who has not endorsed a candidate yet for this election, estimates that even if all the newly registered black voters were to cast ballots in favor of Mondale in November, Reagan would still win New Jersey by 200,000 votes.

Republicans like to point out that Ms. Ferraro, during her tenure as a United States representative from New York, fought to allow New York City to dump sewage in the ocean within a radius that New Jersey politicians say pollutes the state's shoreline. This may dampen her appeal here, they say.