When candidate Jimmy Carter proposed a White House conference on how to strengthen the Americans family four years ago, it had the political appeal of a nice warm dish of mom's apple pie.

Little did he dream that his 1976 campaign brainstrom would reemerge during his 1980 reelection bid as the catalyst for a "new right" effort to rally the country behind a banner of conservative "pro-family" issues -- including keeping the government out of family life.

But that is what appears to be happening as the final planning gets under way for his White House Conference on Families, and some conference planners, claiming they've bent over backwards to be politically neutral, are worried about the ideological fervor from the far right.

Antiabortionists, antifeminists, religious fundmentalists and others who call themselves family "traditionalists" -- supported by conservative political activists -- are organizaing all over the country to elect as many of their sympathizers as possible to the conference.

They won surprise victories in two of the three statewide delegate-selection meetings that have been held so far, routing the representatives of mainline family service organizations who had been expected to set the tone for the state and national gatherings.

It started in Virginia last November where the "pro-family" forces, activated by a highly effective informational network, captured 22 of 24 delegate positions. Later, in Oklahoma, they swept all eight spots. In South Dakota, the mainliners apparently prevailed, although conservatives claim at least one sympthizer among the four delegates.

The conservatives are poised to mount challenges in at least half the rest of the states, according to Connaught Marshner, who serves as chairman of the "pro-family coalition" that was formed as a rival to the Coalition for the White House Conference on Families, the conference's main support group.

"There's no question that they've mobilized around the country," said Joseph Giordano, vice chairman of the latter coalition, which includes groups ranging from the American Red Cross and Future Homemakers of America to the National Gay Task Force. "It's clear the conservative groups are making this a real priority," said John L. Carr, executive director of the conference.

With most states planning to hold statewide or regional delegate-selection meetings in February and March, both sides agree its too early to assess the likely impact of the conservative crusade on the conference, which will be held in June and July in Baltimore, Minneapolis and Los Angeles.

But they agree that family-related issues -- and not just the familiar lightening rods of abortion and equal rights for women -- have enormous appeal because they touch people so directly and personally. The very fact that a White House conference was called, they note, indicates deep concern over both the well-being of the family as an institution and the government's impact on it.

Although Carter may have been first to adopt families as a campaign theme (partly as an antidote to the troublesome abortion issue), the conservatives were quick to co-opt the "pro-family" label for themselves.

Their issues range from school textbooks and classroom prayer to feminism, homosexuality, permissiveness and big government. Sensitive but seemingly nonpolitical issues like parental authority were embraced as conservative causes. Governmental jargon, red tape and efforts to accomodate minorities and alternative life styles presented handy, appealing targets. Moreover, guerrilla activists of the left were off fighting in other wars, leaving it to social work professionals to confront Phyllis Schlafly and her legions in the political trenches.

Ironically, the conference fight stems in part from feminists' domination of the 1977 National Women's Conference and their foes' counter-rally under pro-family colors. "Revenge," said one liberal. "Experience," said a conservative.

Conservatives claim they've been shut out of the family conference at every opportunity, a charge that conference planners deny. But conference rules require that at least 30 percent of the delegates be elected, (the rest will be appointed, some by governors, some in other ways), giving conservatives an entree they couldn't refuse, despite philosphical objections to the conference itself as symptomatic of goverment meedling in family life. "It's out money too," said Marshner, "and we decided we might as well participate."

Marshner herself is an example of the importance that the "new right" attaches to family-related issues. She is editor of the Family Protection Report, a newsletter published by the Committee for the Surivival of a Free Congress, a conservative advocacy organization.

Howard Phillips, national director of the Conservative Caucus, said he's circulating information about the conference to the caucus' 350,000 members, many of whom, he said, are keenly interested. "It's going to be one of the significant issues of the '80s," he said, adding that conservatives owe President Carter a thank-you for giving them such a good target.

On the other hand, planners for the conference, which barely survived an earlier imbroglio over appointment of a divorced woman for the director's post now held by Carr, are worried that such ideological fires might consume the whole conference. "If it becomes the prisoner of one extremist group or another," said conference chairman Jim Guy Tucker, a former Arkansas congressman, "the entire value of the conference would clearly be destroyed."