A coalition of 80 conservative groups yesterday announced a campaign to lobby for passage of the Reagan administration's entire block grant program as part of an effort to "defund the left," which the groups maintain gets substantial financial support from the federal government.

Howard Phillips, executive director of the Conservative Caucus and the groups' chief spokesman, said administration tax and budget cuts "are not nearly so important as eliminating the power of the federal bureaucracy, through categorical grants, to subsidize activist organizations which are working through the courts, the bureaucracy and the culture to render irrelevant the election returns."

The groups, representing a cross section of the New Right, singled out Planned Parenthood, Operation Push, the National Council of Senior Citizens and the National Urban League as liberal organizations receiving federal funds. All administer local job, education, counseling and education programs which receive federal money.

Operation Push, the Chicago-based group headed by the Rev. Jesse Jackson, has received $2 million in federal grants over the years, Phillips told a press conference.

Ron Godwin, executive director of the Moral Majority, said conservatives should adopt a new cheer: "Defund the left. Defund the left.Rah, Rah."

President Reagan originally proposed taking money now given to a host of health, education and job programs and putting it into block grants to be awarded to states with no strings attached. But the president's proposals were considerably watered down in the budget reconciliation bills passed by the House and Senate last week.

Phillips, however, said Senate Majority Leader Howard H. Baker Jr. (R-Tenn.) has promised to use "other opportunities in the legislative process" to allow votes on the block grant issue. Spokesman for Baker confirmed this.

Among other groups in the coalition are American Life Lobby, Citizens for Reagan,Citizens for Limited Taxation, the Eagle Forum, Religious Roundtable, Young Americans for Freedom, and Holiday Inns, Inc., the giant motel chain.