CLEVELAND -- With a year to go until their national convention, Democratic state party chairmen say that the Iran-contra affair has helped to "level the playing field" for the 1988 presidential race, but that their candidates will be better off focusing on a growing apprehensiveness among voters about the nation's economic future.

Most say they doubt that "rule of law" and "decency in government" campaign appeals will retain a strong grip on the electorate's attention once the Iran-contra hearings fade from the television screen. Those appeals were pivotal in Jimmy Carter's win in the post-Watergate election of 1976, the Democrats' only presidential victory of the last two decades.

"Nobody is going to carry Ohio talking about Iran-contra," said James Ruvolo, Ohio Democratic chairman and host to last weekend's meeting of the Association of State Democratic Chairs. "There will be 10 other issues before the first vote is cast in 1988 that will be more important. Jobs will be No. 1 and education will be No. 2, and everything else will be 10."

Richard Wiener, head of the association and chairman of the Michigan Democratic Party, speculated that the affair would "revive a cyclical tendency the public has not to trust Republicans," but most of his colleagues characterized the likely damage to the GOP more modestly: as eliminating a positive rather than creating a negative.

"It has taken some of the glow away from Reagan, and without that happening, whoever the Republicans nominated could have run a 'four-more-years' campaign," said Peter Kelly, chairman of the California Democratic Party.

Party chairs who participated in a group discussion arranged by The Post split generally along regional lines over how their candidates should craft their economic appeals -- and their differences suggest that an economy with pockets of strength and weakness will complicate the "out" party's efforts to fashion a single economic message.

Chairmen from Ohio, Illinois and Pennsylvania, states coping with a shift in their economies away from heavy industry, said that candidates could carry their states talking about an activist government with new programs to take on the problems of job loss. But southern and Sun Belt party leaders flinched at the notion of rhetoric that sounds too gloomy or policies that seem too expensive.

"People don't want to hear that in North Carolina," said Linda Ashendorf, vice chairman of that state's Democratic Party, as colleagues from Florida, California and New Jersey nodded in agreement. "The cities in my state have a 2 or 3 percent unemployment rate. The people still want to hear that it's morning again in America."

Perhaps because they are unsure of the right tone, the leaders said they think their greatest strength in 1988 will be the "messenger, not the message" -- this despite the current lack of national stature by all of their candidates except Jesse L. Jackson.

"Look how long it took the American people to embrace Ollie North," said Larry Yatch, chairman of the Pennsylvania party. "All of four days."

"The people want a tough, strong, take-charge individual, and from our talented field, someone will break out," said Laurence Kirwan, New York chairman.

"I like our hand," said Ruvolo. "We have a clean slate to work on."

Although eight announced or prospective presidential candidates gave speeches here last weekend, and the event drew two days of saturation coverage in the local news media, interviews with voters in ticket-splitting neighborhoods in and around this city immediately afterward showed how clean a slate most of the candidates really are.

"There's still a year to go," said Shirley Siemer, an accountant from Fairview Park, west of Cleveland, defending her inability to name any of the Democratic candidates. "I figure I've got plenty of time to watch them all on TV."

Other voters were more concerned by what they saw and heard. "I'm really discouraged about the candidates that have come forward since Gary Hart went down," said Tom Ambroziak, 39, a high school teacher and a Democrat. "People seem to be crawling out of the woodwork. I don't think they even think they can win. They just want to move up the ladder."

Jackson was the only one who drew anything beyond blank stares or shrugs -- and his notices in Cleveland's 11th Ward, an ethnic area on the eastern edge of the city, were nothing to brag about. "I may be a little prejudiced, but he seems like a cocky so-and-so," said Frances Kolene. Several of her neighbors expressed pique at Jackson for jumping on the Cleveland Indians baseball organization last week for not replacing the manager it had just fired with a black man.

He did better among the party leaders. "You're looking at a different Jesse Jackson this year," said Vincent DeMuzio, the Illinois chairman. "He's more of a regular Democrat. He's ready to do whatever is necessary to help the party win." DeMuzio's colleagues in other states also spoke approvingly of Jackson's toned-down rhetoric, but several said he would remain an albatross to the party because voters' opinions of him are already formed. "He scares people," said one, who asked not to be identified.

Aside from Jackson, the biggest current concern of the party leaders is the upcoming battle over the confirmation of U.S. Appeals Court Judge Robert H. Bork to the Supreme Court.

"This appointment may be the most dangerous thing out there," said DeMuzio. "I'm afraid we're going to send all our lightning rods out there -- the feminists, the 'pro-lifers' -- and it will afford the other side the opportunity to exploit it."

New Jersey Chairman Raymond Durkin said he thinks the nomination places Sen. Joseph R. Biden Jr. (D-N.J.) in an especially difficult spot. "If he doesn't handle it right," Durkin said of Biden, who will chair the confirmation hearings, "it could be his Waterloo." Asked what he meant by "right," Durkin said: "He has to be fair."

In the swing neighborboods, Bork is still a fuzzy name, although a few voters already see the issues in a light that Democratic leaders seem anxious to cast: "Bork is going to take us backwards," said Bill Hesselton, 36, a heavy-hardware salesman. "I think women ought to get equal pay."

Residents had much more vivid feelings about the Iran-contra affair, and they tended to personalize them around their support for Lt. Col. North and their criticism of the congressional investigating committees and their lawyers.

They also expressed a generalized disillusionment with the entire political process, and some laid their concerns at President Reagan's feet. Frances Miller, 75, a self-described "Harry Truman Democrat," said she had felt "very confident" about Reagan until the affair broke, and now feels "confused, very confused" about the nation's leadership. "I just don't feel as secure as I did."

Democratic strategists say they believe that the downturn in various indices of public confidence over the past eight months is related, at least indirectly, to a disappointment with Reagan that many voters can barely bring themselves to express.

In last month's Washington Post-ABC News poll, the share of people who said they think the nation is on the wrong track was 62 percent, those who expected the economy to get worse exceeded optimists 38 to 19 percent, and those who had more confidence in the Democrats to handle the nation's pressing problems outranked those with faith in the Republicans by 47 to 41 percent. All of these represent an increase in disaffection.

On the other hand, North's personal appeal appears to have taken the sting out of the public's discomfort with the Iran-contra episode. "I did my own informal poll at the mall," said Ashendorf, who lives in Charlotte, "and when I got home I wanted to cry. Nine out of 10 people I talked to thought he should run for office."

And any Democratic campaign theme built on pocketbook appeals will bump into an image problem the party still has not erased. Hesselton, the salesman, spoke at length about how he thinks needs for housing and health care for the elderly have gone unmet during the Reagan years. But the prospect of electing a Democrat didn't seem to thrill him.

"The Democrats stand for give-aways," he said. "If we elect one, my taxes are going to go up."Staff researcher Lee Kennedy contributed to this report. Voting precincts in the Cleveland area were chosen with the help of Richard Scammon of the Elections Research Center.