These should be sweet days for liberals. Congress is overwhelmingly Democratic, the President is a Democrat who cites Franklin D. Roosevelt as a spiritual predecessor, and both branches of the federal government work against a backdrop of 25 years of court decisions that have tilted heavily in the direction of more civil liberties - Brown v. Board of Education in 1954, the constitutional right to abortion in 1973.

However, "it's not all peaches and cream" for liberals today, says Leon Shull, national director of Americans for Democratic Action, an influential, 30-year-old liberal public advocacy group.

In a report to be released today, Shull and co-author Vicki Otten highlight "recent steps Congress has taken to undermine the civil rights gains made in the past twenty years," especially in the areas of busing and abortion.

The report is timed to coincide with a nationwide effort by local ADA chapters to put pressure on members of Congress whom the ADA feels have been slipping from liberal doctrine in their voting records.

The ADA declined to pinpoint members whom they feel have turned their backs on liberal constituents, saying that will be the job of local organizations.

"Our special concern," said Shull, "is that the civil rights and civil liberties community has not been making itself heard, while the rightist groups have."

"We have got to be as organized as the right is," said co-author Otten. "It's not enough to be protected by the laws and the courts - what we are seeing is a whittling away at the civil liberties progress that's been made."

That "whittling away," according to the report, comes mostly in the form of congressional refusals to appropriate federal money to judicially sanctioned actions - namely, busing and abortion.

Busing, which has long been advocated by liberals and sanctioned by the courts as a judicial tool for desegregating schools, suffered a major set-back in 1975 with passage of the Byrd amendment. Sponsored by now-Senate Majority Leader Robert C. Byrd (D-W.Va.), the amendment prohibits the Department of Health, Education and Welfare from forcing school districts to bus children beyond the school nearest their home for racial purposes.

Then, on June 16 of this year, the House passed what the ADA report terms "an additional attempt to hamstring HEW's school integration efforts."

The amendment, sponsored by Rep. Ronald M. Mottl (D-Ohio), would prohibit HEW from withholding funds from school districts that refuse to consolidate or "pair" schools to achieve racial balance.

These recent actions reflect a major change in legislators' perceptions of the busing issue, according to the ADA's Otten.

"The anti-busing fight is no longer being led by the Eastlands and the Stennises," she said, "but, now, it's the Eagletons and the northern liberals.

"For northerners, busing used to be a moral issue," she said. "But now they look at it happening in their own districts and they respond to their constituents rather than to the guaranteed constitutional right it is for poor children."

Since the 1973 Supreme Court decision that it is unconsitutional to prohibit abortions. Congress has considered three versions of an amendment to the Constitution to override the decision.

In addition, the ADA report stated, about 19 per cent of the members of the House have sponsored some form of anti-abortion legislation.

The Hyde amendment, a bill sponsored by Rep. Henry J. Hyde (R-Ill.) to deny Medicaid money for abortions except in cases where the mother's life is endangered, has stirred nationwide controversy. It is law now, and the ADA report attributes its success in part to anti-abortion votes by new members, "contrary to the pro-choice positions they expressed during their election campaigns."

According to an ADA survey of congressional voting records, 37 per cent of the House voted the liberal position on the five issues used in the 1977 test. In the ADA's 1976 rating of votes on 20 issues, 44 per cent voted the liberal position.

The survey shows that "the Senate has voted less conservatively on civil rights issue" than it voted on all issues in 1976. In 1976, the overall Senate average of liberal votes was 45 per cent; on civil rights this year, 49 per cent.

"One of our objectives with this report," said Shull, "is to alert supporters of civil rights and civil liberties that this is going on - that some members of Congress who have always had support of the liberal community are voting differently now.

"In part," he added, "I guess it's because the civil rights advocates of the sixties have come to feel their battles are won. There's always a little bit of a dialectic at work here."