An angry band of conservative delegates stalked out of the White House Conference on Families today after a liberal-moderate coalition easily pushed through pro-abortion and pro-ERA resolutions in preliminary voting on conference positions.

The conservatives, led by Connie Marshner of the National Pro-Family Coalition and Lawrence D. Pratt, a Republican member of the Virginia legislature, totaled about 50 people, but Pratt said he expects another 50 or so to boycott the conference later. This is only a small fraction of the 671 delegates from eastern states attending the first of three regional White House conferences on the family.

Marshner, presiding over an open caucus in the hall of the convention center just before the walkout, shouted, "By walking out now the points will be made that the conference does not have credibility. They are pro-ERA, pro-abortion, pro-sexual preference, pro-a guaranteed annual income, and pro-national health insurance."

Pratt repeated charges that the White House and conference chairman Jim Guy Tucker had "rigged" the conference's membership to assure a liberal majority.

Pratt then led the band into a hall -- where pollster George Gallup was addression a luncheon meeting -- with the intention of marching the 50 conservatives in, shouting that they were leaving and them dramatically walking out. But the luncheon adjourned a few moments early. Nevertheless, Pratt wrestled the microphone from Tucker's hands and shouted, "We decided this delegation is stacked and we should walk out."

Earlier, the conservatives suffered one crushing defeat after another in policy voting at the subcommittee stage. They had favored an anti-abortion plank, but one subcommittee overwhelmingly adopted language in favor of the right to abortion for low-income women. The same subcommittee endorsed the Equal Rights Amendment, and it declared there should be no legal discrimination against people with "special preferences" in family life -- a veiled reference to homosexual households.

All three of these policy recommendations were anathema to the Pratt-Marshner group.

Another subcommitte voted 28 to 18 to endorse a proposal saying that "the full range of family planning services, including pre-and-postnatal care and safe legal abortions, must be available to all who make this decision."

In another panel, an attempt by Pratt-Marshner supporters to declare that only heterosexual families are worthy of the title "families" was defeated, 22 to 15.

Attempts by gay rights advocates to write a definition of family that would include homosexuals lost, 20 to 18, so the final recommendations will not contain a precise difinition of families.

The Pratt-Marshner group has made clear in a round of news conferences that it believes that abortion, public welfare spending beyond a certain point, national health proposals, homosexuals rights and similar features of what the group views as the permissive liberal state are undermining the traditional family.

Marshner told reporters this morning that she favors "abstinence," adoption and making the father financially responsible as ways of dealing with teen-age pregnancy.

After the walkout, conference chairman Tucker said he regretted that a handful of delegates decided to leave, but said "the vast majority of delegates are remaining" and they "still represent the vast majority of people in this country."

He said that 83 percent of the delegates had been chosen by the states and governors and that a person would have to believe that "every governor in the East was in conspiracy" to believe that delegate selection had been rigged.

After the walkout, the two subcommittee recommendations in favor of abortion were approved by full commitee panels by even bigger majorities, 105 to 27 and 73 to 24. The language in favor of ERA and against discrimination for sexual preference was included in the 73-to-24 vote. However, all or part of this language could be dropped Saturday when the full conference takes final votes.