Boston — Students and liberal activists are well represented among supporters of independent presidential candidate John B. Anderson. But how much larger is the Illinois congressman's constituency?
Political analysts generally agree his strength is greatest among highly educated, at least moderately affluent, and suburban voters.
A late-August survey by the Roper Organization found that while Mr. Anderson's overall voter preference level was 18 percent, his popularity was greater within several important groups.
Among liberals, 31 percent preferred Mr. Anderson to either Democratic President Jimmy Carter or Republican nominee Ronald Reagan.
The greater Anderson appeal among younger and young-to-middle-age voters is indicated by his 24 percent support within the 18-to-29 age group and 22 percent backing by 30- to 44-year-olds.
Other groups where Anderson backing exceeded his average include political and social activists, employed women, persons holding executive positions or engaged in professions, college graduates, Roman Catholics, and residents of urban or metropolitan areas.
In contrast, Anderson rated poorest among rural voters, where his support level in the Roper survey was 3 percent. His other weak areas were 8 percent among those with less than a high-school education, 7 percent among those with annual incomes less than $7,000, and 12 percent among self-described conservatives.
Nineteen percent of all women surveyed said they favored Anderson, compared with 17 percent of the men expressing that preference.
His level of support among those in the second-highest income bracket increased to 20 percent, and to 22 percent in the highest.
Particularly challenging to the Anderson campaign effort is the solidity of the independent's support. The Roper poll, for example, found that while 92 percent of those who favored Mr. Reagan insisted they are all but sure they will stick with him, and 85 percent of those favoring Mr. Carter similarly expressed their commitment, only 53 percent of the voters who said they preferred the Illinois congressman were sure they would stick with him.
The latest Harris poll indicates that support for Anderson may hinge on how voters perceive hi prospects for victory.
The Anderson overall preference of 17 percent climbed 9 points when those questioned were asked how they would vote were they to feel he had a strong chance of winning. Under such circumstances, Reagan was favored by 39 percent, Carter by 32 percent, and Anderson by 26 percent.
Under the same conditions, Jewish voters queried increased their support from 31 to 48 percent, a 17-point gain. At the same time, the Carter preference within that group dropped from 40 to 26 percent and the Reagan support climbed from 18 to 19 percent.
Although Anderson's pull within the ranks of organized labor had been perceived as an era of potential weakness, he polled 22 percent support from this segment of the electorate in the Harris poll. Given a chance of winning, his support level climbed by another 11 points.
Anderson appears weakest in the South, which many account for his low rating among rural voters in the Roper poll. Areas of his greatest appeal are the Northeast and Far West, trailed by the Midwest.
A significant portion of the Anderson constituency, as they and others view it, is among people who might not otherwise vote. Besides independents, moderate and liberal Republicans and issue-oriented Democrats are being wooed.