PORTLAND, ORE. -- From its beginning 16 years ago, the National Women's Political Caucus has been pro-choice. On the issue of reproductive freedom, including the abortion option, the caucus and the women's movement remain single-minded and strong.

But the biennial convention here last week showed that the 1,000 or so delegates -- and presumably the 77,000 other activist women who belong to NWPC's state affiliates -- are struggling with other choices.

The Republicans in the caucus, who call themselves moderates or progressives, are weighing whether they can remain both feminists and loyal Republicans.

Democratic women members, almost all of whom fall on the liberal end of the spectrum, are torn between the emotional appeal of the prospective presidential candidacy of Rep. Patricia Schroeder (D-Colo.) and the practical considerations that have taken many of them into leadership roles in the campaigns of the seven male contenders.

The mood of the Republican women was captured in the button worn by Sharon Hageman of Riverside, Calif., head of NWPC's resolutions committee. Between an elephant and an equal-rights symbol were the words ''It ain't easy.''

Republican women of the NWPC feel they are being shunned by their party. Kay Orr of Nebraska, the only new woman governor elected last year and the head of the 1988 Republican platform committee, did not come here to discuss the issues. Nor did Maureen Reagan, an avowed feminist who is cochairman of the national Republican Party.

All the prospective presidential candidates were invited; five Democrats and no Republicans accepted. The GOP gentlemen, said Mary Stanley of Fresno, Calif., cohead of the GOP women's task force, ''are afraid to come here because word might get out to the new-right, Ronnie-come-lately Republicans that they said something we liked.''

Nor did any of the prominent Republican women attend: not the widely admired Elizabeth Dole, one of the ''founding mothers'' of NWPC, nor the much-loved Mary Louise Smith, former Republican national chairman and leading supporter of George Bush.

Tanya Melich of New York, a founder of NWPC and veteran Rockefeller Republican, told fellow partisans that after years with ''a split personality, I have decided the stress and strain of being effective both as a Republican and a feminist are too difficult.''

For now, Melich said, she is going to subordinate feminism, ''support the nominee, be a good loser and then move in.'' In time, she said, she and like-minded people may be able to wrest control of the GOP from conservatives -- and even ''elect a woman Republican president by the year 2000.''

Others are discouraged that not one Republican presidential contender is running on a pro-choice, pro-Equal Rights Amendment platform. They are planning either to sit it out in 1988 or to put their feminism first by supporting Schroeder. Martha Ezzard, who made a credible losing run for the 1986 Republican senatorial nomination in Colorado, quit the legislature last month and switched parties. Several other GOP women, from Washington, D.C., to Marin County, Calif., said they were contemplating enlisting for Schroeder.

Ironically, many of the Democratic women flinch from the choice presented by the possible Schroeder candidacy. She drew cheers here, but party activists and public officials -- up to the level of Gov. Madeleine Kunin (D-Vt.) -- who have endorsed other candidates made it clear in interviews that their previous commitments would stand.

Ann Lewis, the head of the Democratic women's task force and an adviser to Jesse Jackson, said, ''There's a strong feeling Pat ought to be running, that the field would be better with her in it. But the women with power bases and commitments of their own are not saying, 'I will be there.' ''

Irene Natividad, head of NWPC, told me that endorsement of Schroeder by the caucus would not be automatic. ''If Pat runs, we'd go through the same process we would with any other candidate,'' she said. ''We'd look at the viability of her race, her funding, how she stacked up against the other candidates. We've reached that state of maturity.''

On issues as well as candidates, the woman activists have moved beyond symbolism. When convention speakers mentioned the ERA, there was none of the fervent shouting of those initials one heard at earlier NWPC conventions. ''It doesn't have the same emotional intensity,'' Lewis said. ''It remains an important symbol, but people are much more focused on electing more women to office at all levels, making our impact felt on the presidential platforms and campaigns and defeating the {Robert} Bork nomination.''

In a similar vein, Republican Hageman said she found this year's NWPC resolutions debates (from which the press was excluded) ''less strident, more focused than ever before.'' A proposed constitutional amendment to allocate half the House and Senate seats to women got short shrift in her committee. ''I simply asked the sponsor if she wanted me to work against Pete Wilson {the Republican senator from California} at the same time I'm lobbying him on the Bork nomination, or did she propose to double the size of the Senate,'' Hageman said.

Symbolism is out. Hard choices and hard-boiled judgments are in