The last two months were strange ones in this most conservative Senate in a quarter century.

Two moderate Republicans -- both of them prickly mavericks -- grabbed control of the Senate. They moved out in front of the better-known liberal Democrats in the Senate and filibustered the New Right into the ground on its two big issues of restricting abortion and promoting school prayer.

Behind these moderates was one of the unlikeliest senatorial lineups of all time, ranging from a backbench Democrat from Montana to a windy neo-conservative from New York to old "Mr. Conservative" himself, Barry Goldwater (R-Ariz.).

The most formidable group lobbying on the moderates' side and against the prayer and abortion amendments was a fairly stuffy organization seldom heard on such explosive social subjects: the American Bar Association. And when the Senate voted on school prayer, the Moral Majority didn't show up.

The two moderate GOP filibuster leaders were Sens. Lowell P. Weicker Jr. of Connecticut, a fiesty and bombastic fellow unpopular among his colleagues, and Bob Packwood of Oregon, the independent-minded chairman of the National Republican Senatorial Committee.

Weicker became the dominant figure on the civil liberties side of the debate and showed himself to be a master of Senate rules; Packwood was the leader on abortion.

On the Democratic side, moreover, such familiar liberal figures as Sens. Edward M. Kennedy (Mass.) and Alan Cranston (Calif.) were rarely heard. Instead, the Democrats were led in the filibuster by Max Baucus (Mont.) and Daniel Patrick Moynihan (N.Y.). Their main opponent on the New Right side of the debate was Sen. Jesse Helms (R-N.C.).

The filibuster tied up the Senate from Aug. 16 until Sept. 23. It was punctuated by 10 votes, none on abortion or prayer per se but rather on parliamentary questions -- whether to limit debate, whether to table a pending amendment. Helms' forces won only one of these. Time after time, Republican moderates -- such as Sens. Charles McC. Mathias Jr. (Md.), John Heinz (Pa.), Arlen Specter (Pa.) and John H. Chafee (R.I.) -- joined Democratic liberals in beating back Helms.

Helms said the prayer and abortion votes should dispel the notion that the Senate is controlled by conservatives. There are no more than 35 solid conservatives in the body, he said. "Republican it is," he said of the Senate, but "conservative it ain't."

But Helms also lacked united support among conservatives; such staunch ones as Sens. S.I. Hayakawa (R-Calif.), Warren Rudman (R-N.H.) and Slade Gorton (R-Wash.) deserted him. His problem was that for many senators the issues at some point ceased to be abortion and prayer and became instead the Constitution.

The debate was not one of Republicans versus Democrats or liberals versus conservatives so much as the moderate center standing up for the Constitution against "the radical right." Two elements were key:

"The Goldwater factor." The crusty Arizona Republican has no patience with the New Right or its attempts to legislate morality. His opposition to Helms made it possible for other conservatives to oppose him as well. "I am getting tired of hearing about the New Right. I am just an old fashioned conservative," he said at one news conference. "I don't like being called New Right. I'm just an old, old son of a bitch. I am a conservative."

The ABA's role in the fight.

Helms' anti-abortion amendment declared the Supreme Court "erred" in its 1973 decision on abortion, and set up machinery for quick Supreme Court reconsideration of the issue. His prayer amendment would have kept federal courts from overturning state laws allowing prayer in public schools.

The ABA leadership and such conservative constitutional scholars as Robert H. Bork, now a U.S. Court of Appeals judge, agreed with civil liberties groups that the proposals were attempts to strip federal courts of authority.

Letters from the ABA castigating Helms' proposals were entered into the Congressional Record during the long filibuster. In a body dominated by lawyers, they were potent stuff. Republican Specter, for example, is a former Philadelphia district attorney; Rudman a former New Hampshire attorney general; Gorton a former Washington attorney general. "I don't understand how any lawyer worth his salt could vote for amendments like these," said one senator, a lawyer. "They make a mockery of the Constitution."

Meanwhile, the coalition that the ABA had joined was gathering steam across the country. Called the Ad Hoc Coalition to Save the Federal Courts, it was formed in the winter of 1981, and has met at 2:30 p.m. almost every Monday ever since in Room 2141 of the Rayburn House Office Building, the home of the House Judiciary Committee.

The meetings are chaired by John Shattuck, the American Civil Liberties Union's Washington director. They included representatives of Common Cause, the Leadership Conference on Civil Rights, ABA, National Abortion Rights Action League, Planned Parenthood Federation, organized labor, National Organization for Women, the Religious Coalition for Abortion Rights, Jewish and Protestant religious groups, and others. They provided a skilled corps of lobbyists here and an army of thousands out in the field.

In essence, the group represented a rebirth of the old coalition that pushed for civil rights legislation in the 1960s. Ralph Neas, executive director of the Leadership Conference on Civil Rights, says its strategy was "to build as broad a coalition of Republicans, Democrats and conservatives as possible" and to "isolate the far right from the mainstream of the Republican Party."

Most of the same groups teamed up in the successful effort earlier this year to extend the Voting Rights Act. By the time the anti-abortion and school prayer fights reached the Senate floor, they were a well-oiled lobbying machine. Their opponents were in disarray. "We learned the other side was divided and not very sophisticated," says Shattuck of ACLU. "They really weren't very effective."