Rep. Stephen J. Solarz set forth the outlines yesterday of an "emerging Democratic foreign policy consensus" that he said places his party in a more internationalist posture than it was a decade ago, but that assails the Reagan administration for intervening in Central America and Angola.

In a interim report to the Democratic Policy Commission, the New Yorker, who chairs a task force drafting an unofficial foreign policy statement for the party, also criticized the administration for a "too little, too late" policy of "watered-down" economic sanctions against the apartheid regime in South Africa and for "belated" recognition that "tyrannies of the right are just as hateful as tyrannies of the left."

Rep. Les Aspin (D-Wis.), chairman of the House Armed Services Committee, told the commission that the administration has engaged in "the most expensive bluff in history" by spending $1 trillion on a defense buildup that has left the military only "marginally" stronger.

And Sen. Gary Hart (Colo.) told fellow Democrats that their party "cannot be defensive about defense" and should continue to hammer at Defense Department procurement scandals, mismanagement of military personnel and "disastrous" naval strategies.

The day of speechmaking previewed the lines of attack Democrats will wage in this year's elections and the 1988 presidential race.

The policy commission, set up by the Democratic National Committee last summer, is scheduled to issue its final report on foreign and domestic policy this summer.

Yesterday's speeches and panel discussion made it plain that Democrats are united in saying that defense and foreign policy issues have cost them elections in the past decade, and they agree that they must attack the administration in these areas from a posture of strength.

"We are not soft on communism. We are not weak on democracy . . . . We don't need to hang our heads," Hart told a roomful of activists.

"Don't let anyone get away with saying that Democrats are weak on defense," said Sen. David H. Pryor (Ark.).

Solarz, summarizing the work of the foreign policy task force, said the party today is more willing than the post-Vietnam party of a decade ago to talk about use of force and assistance to anticommunist insurgencies and to point fingers at Soviet violations of arms-control agreements.

However, on the question of military aid to the contras, or counterrevolutionaries, in Nicaragua, Solarz said his task force opposes the administration's "futile attempt to impose a military solution via the contras" and favors a regional diplomatic approach.

In Angola, Solarz said, the administration's support of the South Africa-backed Jonas Savimbi "tarnishes" the list of "freedom fighters" it is backing. He said Democrats favor aid to Afghan mujaheddin, Solidarity in Poland and Soviet Jews.

In the arena of arms control, Solarz called for a policy of not undercutting the SALT II treaty as long as the Soviets observe the same policy; ratification of the Threshold Test Ban Treaty and the Peaceful Nuclear Explosion Treaty, both negotiated by Republican presidents in the 1970s but not backed by this administration; and negotiations with the Soviets to ban antisatellite weapons development.