Democratic presidential candidate Richard A. Gephardt was foraging for campaign funds in the affluent suburbs of Atlanta, but he was speaking in the language of a state 870 miles away: Iowa.

"The heart of America is being torn out," Gephardt told the slightly incredulous group of brokers, bankers and investors, whose fortunes have been steadily rising with the bullish stock market.

To illustrate, Gephardt described the plight of an Iowa farmer facing bankruptcy who returned home one day and went looking for his son to do some chores. "He couldn't find him," Gephardt said, "so he went to the barn, and there he found his son hanging from the highest rafter."

While the story produced a resounding silence from Gephardt's audience, it underscored how much presidential candidates gear their speeches to a special universe of voters: those who are likely to attend the Iowa precinct caucuses Feb. 8 and those who are expected to vote in the New Hampshire primary eight days later.

Uniquely empowered to define front-runners, weed out the weak and convert long shots into contenders, the electorates in Iowa and New Hampshire are in many ways atypical of voters nationwide. For the candidates of both parties, these two electorates create conflicting pressures: caucus participants in Iowa tend to be more liberal than the electorate as a whole, while New Hampshire voters tend to be more conservative. Recent economic experiences of these two states have reinforced those tendencies.

"The most compelling difference {between Iowa Democratic caucus-goers and New Hampshire Democratic primary voters} is that in Iowa, you are dealing with a universe of people who think we as a country have been doing the wrong thing for the last eight years and we are suffering from it," one Democratic pollster said. "In New Hampshire, voters think we've been doing some right things, and we'd like to be more right in order to preserve what we've got. "

Of the two electorates, the roughly 100,000 men and women who participate in the Iowa Democratic caucuses are at the farthest extreme from national norms, according to three polls conducted for Democratic presidential candidates. The caucus-goers, according to the poll data, are far more liberal, pessimistic and antiwar than Iowa or national Democrats in general.

"The Iowa {Democratic} caucus participants are discouraged, alienated and frustrated. They are overwhelmingly pessimistic about America's direction and hold {President} Reagan responsible," said another Democratic pollster who recently conducted a survey of past attendees for one of the 1988 presidential candidates. "These people {caucus-goers} are by definition not just participants but activists. They are alientated activists."

"There is a statewide sense of desperation that things are on the wrong track," another pollster said. "Most Democrats are not happy with the way the country is moving, but in Iowa there is an emotional fuel to the feeling."

One indication of how sensitive campaign operatives are to the voters in Iowa is that these Democratic pollsters declined to allow their names to be used because they did not want to link the candidates employing them to any comments that might be viewed as critical of the Iowa electorate.

A comparison of recent polling data shows the disparity between Democrats who participate in the Iowa caucuses and Democrats in general. According to recent Washington Post-ABC News polls, voters nationally say they believe the country is going in a wrong direction by slightly less than 2 to 1, while Democrats nationally say that by a 3 1/2 to 1 ratio. But a private poll of past Iowa Democratic caucus participants shows that they believe that the country is headed in the wrong direction by 7 to 1.

A poll of Democratic caucus attendees in Iowa taken last March showed intense opposition to aid for the Nicaraguan contras. When asked whether they would be more or less willing to support a presidential candidate who would "cut off all aid to the contras fighting the communist government of Nicaragua," the Iowa Democrats opted for the aid cutoff by 72 percent to 16 percent.

At this stage in the 1988 election process, far more information is available about Iowa Democratic caucus participants than either their Republican counterparts or the electorate in New Hampshire. This is because the Iowa Democratic Party maintains a list of who attended caucuses in 1984 and 1980.

In New Hampshire, the electorate is far more fluid because the state holds a primary rather than a caucus. Tracking voters in New Hampshire is also difficult because there has been a large influx of new residents in the southern half of the state. But a number of conclusions can be drawn from polling data and interviews with campaign workers, consultants and economists:For Republicans, the Iowa electorate is considerably more moderate than New Hampshire's GOP primary constituency, according to pollsters working for competing Republican campaigns. As a result, the Iowa Republican electorate is far less supportive than the New Hampshire electorate of key elements of the Reagan agenda, including the president's Strategic Defense Initiative (SDI), the missile defense system known as "Star Wars," stepped up defense spending, and continued tax cuts.

A series of polls of Iowa Republicans taken over the past three years found that a slight majority opposed aid to the contras, well before the Iran-contra scandal emerged; that only 5 percent of Republicans thought cutting taxes was the way to solve economic problems; that 60 percent supported cuts in defense spending, and that GOP voters were evenly split over SDI.

These findings pose significant problems for the candidacy of Rep. Jack Kemp (R-N.Y.), who, of all the candidates, is one of the most vocal supporters of SDI, increased defense spending, aid to the contras and cutting taxes. Consultants for Democratic and Republican candidates believe that the New Hampshire electorate -- Republican and Democratic -- is far more opposed to tax increases than participants in the Iowa caucuses.

In New Hampshire there is a long history of antitax policies. In 1986 New Hampshire's state and local taxes as a percentage of the personal income were by far the lowest in the nation: 8.23 percent. In contrast, Iowa, at 11.02 percent, is very close to the national average of 11.37 percent.

For the Democratic presidential candidates who must campaign in New Hampshire and Iowa, "taxes is one tough issue to talk about," the pollster for one of the candidates said. "In Iowa, you can go out with heavy populist rhetoric -- 'tax the rich, make them pay their fair share, raise the money to pay for programs people need.' In New Hampshire, you are talking to a lot of people who aspire to be in those income brackets. There is sort of like a 'Whoa, this {populist rhetoric} is what we used to have, what got us high interest rates and high inflation,' " he said.

These differences may be reinforced by the contrasting economic experiences of the two states. Iowa and New Hampshire started the 1980s at rough parity economically. In 1980, per capita income in Iowa was $10,968 compared with $11,132 in New Hampshire, according to the U.S. Bureau of Economic Analysis. However, by 1985 New Hampshire had surged to $13,370 in inflation-adjusted dollars, while Iowa had risen to $11,523. New Hampshire's growth rate was second fastest in the nation, Iowa's 45th.

From 1980 to 1986, the number of jobs in New Hampshire shot up from 450,000 to 569,500, including an increase in manufacturing work, in contrast with the national decline in these higher-paying jobs. In Iowa, the reverse has been true. Nonfarm jobs fell by 52,000. More importantly, the losses were most heavy in manufacturing jobs paying $418 a week, while the number of service jobs paying $203 a week has grown.

There is, however, growing evidence that Iowa is pulling out of its economic slump. "The economy is improving some," said Dennis Starleaf, chairman of the Iowa state economic department. "It appears we've had a kind of turnaround in the agricultural industries," said Jerald Barnard, director of the Institute for Economic Research at the University of Iowa. In the more diversified economies of Des Moines and Cedar Rapids, publishing, insurance and service industries are, in many cases, flourishing, Barnard said.

It is not clear what this shift in the economy will do to politicians whose messages emphasize the threat of a continuing deterioration of the job and farm market. In New Hampshire, however, jobs are so plentiful that some restaurants use employment applications for their place mats, and pessimistic predictions are not likely to work well on the campaign trail. The Iowa Democratic caucus participants include an exceptionally high percentage of men and women who are members of unions, peace groups, local party organizations, liberal farm groups and teachers' organizations.

"It's off the charts," one pollster said, estimating that in Iowa over 40 percent of the Democratic caucus participants are members of such groups, twice as high a percentage as Democratic electorates in northern states that hold primaries. In most southern states, the percentage of Democrats who belong to such groups is about 10 percent.

These groups effectively determine much of the basic strategy about campaigning in Iowa. George Brown of the Iowa Teachers Association said the organization has a political committee of 100 members, each of whom is given a list of all the contributors to the teachers' political action committee. Each member then has a ready constituency to pull together for local meetings with presidential candidates.

"It's more like lobbying than campaigning," said one presidential strategist. Instead of attempting to persuade voters and to present a larger vision, "you go in front of these groups, present your position and effectively get a rating on your stand," he said. The Democratic electorate in the New Hampshire primary is far younger than the universe of caucus participants in Iowa.

In 1984, an ABC exit poll of New Hampshire Democratic voters showed that just 28 percent were over the age of 50. In contrast, a private survey earlier this year of Iowa caucus-goers found that 53 percent were over the age of 50. The private survey was taken three years after the 1984 election, so that the population had aged somewhat, but it still was far older on average than the participants in the New Hampshire contest.

There are a number of political analysts who contend that the relative youthfulness of the New Hampshire electorate was a key factor in the size of Gary Hart's 1984 primary victory there.

Bonnie Campbell, chairman of the Iowa Democratic Party, contends that "Iowa Democrats are a reflection of Democrats nationally. I get a little irked at the suggestion that we are more liberal than Democrats nationwide."

To back up her view, she cites a New York Times survey described in a Jan. 29, 1984, article entitled, "Survey Finds Iowans Are in Political Mainstream." The article said, "On the state of the economy and issues like the risks of war, efforts to reach agreements with the Soviet Union, or whether American Marines should remain in Lebanon, all registered voters in Iowa taken together very closely mirrored the attitudes of people around the nation."

Pollsters working for Democratic candidates said the New York Times poll failed to capture the strong liberal tilt of the Democratic caucuses because it was based on a telephone survey of 1,910 adults, 1,366 of whom said they were registered to vote. Caucus-goers are "a very special universe" who are considerably to the left of most voters in Iowa, and the nation, according to one pollster, whose view was supported by others.

"In Iowa, you are dealing with something that would almost border on a social revolution," said one of the pollsters. "They think this thing {existing government policies and the economy} is all . . . wrong. Running in Iowa, then New Hampshire and then Super Tuesday in the South is a three-cushion shot . . . . The question for the candidates is to keep as many options open as possible."