In the final days before Tuesday's state primary, the campaigns of the three leading Democratic candidates for governor are a collage of contrasting images -- freeze frames from the newsreel of a political party in search of itself.

Click: Candidate John F. Russo, majority leader of the state Senate, is at the National Ukrainian Home here, standing amid the bobbing balloons and fading glory of one of the state's last great county political machines, pleading for votes. If this party "that helped so many of you" nominates a liberal, the self-styled conservative warns the New Frontier Democrats club, it will not "survive" the fall elections.

Click: Candidate Kenneth A. Gibson, the mayor of Newark, is in the pulpit of St. John Baptist Church in Jersey City, gazing approvingly at the Rev. Jesse L. Jackson, who is summoning an enthusiastic, overflow crowd to move Gibson another step up the ladder of power. Gibson said his priorities include "people-oriented" human services -- even though President Reagan's election is viewed by some as a signal to play down such a political approach.

Click: Candidate Peter Shapiro, the Essex County executive, stands in front of a toxic-waste swamp in downstate Bridgeport. Workers in white protective "moon suits" conduct tests while Shapiro calls for an all-out state effort to clean up the environment, modeled after President John F. Kennedy's program to conquer outer space. The reference to Kennedy is designed to reinforce the subliminal messages of Shapiro's massive television advertising campaign, intended to stir up a new "feeling of idealism" among moribund Democrats, in part by glorifying past political heydays.

Most polls show an extraordinarily high proportion of undecided voters in this contest -- as many as 40 percent in some surveys. Gibson and Shapiro generally have run within striking distance of each other for the lead, with Russo significantly behind.

"This campaign has had no depth," said Rep. James J. Florio (D-N.J.), the 1981 nominee, who decided not to run this year, noting that most of the state's major television coverage comes from out-of-state stations and that state law restricts spending to $1.1 million. "This is going to be an organizational effort, an image effort, a low-turnout campaign," he said. About 500,000 to 600,000 Democrats are expected to cast ballots in the six-way primary. The winner could receive as few as 160,000 votes in obtaining the necessary plurality.

Gibson, 53, finished third in the 1981 primary and generally is recognized as having the strongest base, built over 15 years as mayor of the state's largest city, rooted among blacks -- 12 percent of the state's population -- and expanded by voter registration efforts that preceded Jackson's campaign for the 1984 Democratic presidential nomination.

If Gibson wins, he would be the state party's first black nominee for governor, but he is de-emphasizing race at every turn. "I refuse to allow any of the media representatives to put me in a corner," Gibson said. "But anyone who doesn't know I'm black hasn't been in the region."

Russo, 51, has tied his political hopes to the remnants of the party's machine, collecting endorsements from fellow state legislators, mayors, county political leaders and union chiefs and counting on them to turn out the votes.

In many respects, Russo is running as a New Jersey version of the "sensible center" candidacy that Sen. John Glenn (D-Ohio) tried in the presidential primaries in an effort to return moderates to the party's fold. That is a disadvantage in the primary, where most regular Democratic voters are more liberal.

"I'm much better off in the general election than I am in the Democratic primary," Russo said.

Shapiro, 33, must share his natural political base with Gibson, mayor of the largest city in the county that Shapiro runs. But he also is using television to appeal to voters categorized less by interest group and more by age and longtime affiliation with the party.

Seeing the party at a crossroads "in terms of its psyche," Shapiro is spending little time criticizing Republican Gov. Thomas Kean and is trying instead, he says, to offer "new ideas" that will make Democrats "the party that embraces change and forward movement" rather than defending the bureaucracy or attacking the opposition.

The other two mainstream candidates, each given less likelihood of winning the primary, are Robert Del Tufo, 51, a former U.S. attorney, and Stephen B. Wiley, 54, a former state senator.

Many New Jersey political observers say that the state's odd-year gubernatorial election -- Virginia is the only other state having one in 1985 -- is more a contest of local styles than a trend-setter for future national contests.

Personality differences, not ideological clashes, are shaping the generally collegial Democratic battle to be the underdog in next fall's race against Kean, who is unopposed in the Republican primary.

But New Jersey Democrats are facing an apparently growing surge of Republican sentiment and a shrinking perception that their party is best equipped to deal with pressing problems.

The choice of the gubernatorial nominee could affect at least one remaining Democratic power center in a once strongly Democratic state that has voted Republican in the last two presidential contests.

"The major issue is whether the Democrats keep or lose control of the Assembly," said Alan Rosenthal, director of the Eagleton Institute of Politics at Rutgers University. "I don't think most people think anybody's going to beat Kean." Democrats control the state Assembly, 43 to 37, but all 80 seats are up this fall.

Despite the findings of most polls, all three major Democratic contenders see Kean as beatable. Referring to the state's National Football League team, which finished last season with a 9-and-7 record, Russo said of Kean's vaunted invincibility: "The Giants would win every Sunday if the other team didn't show up."