AS WASHINGTON contemplates tax reform and debates trade policy, voters -- or at least Republican primary voters, who may very well choose the next president -- seem interested in other things. What? For one thing, abortion. For another, traditional values generally. For a third, evangelical religion.

The evidence for this comes from the startling election results in some of the unlikelier places. In Oregon, which has produced progressive Republicans such as Tom McCall and Wayne Morse (who eventually became a Democrat), Republican primary voters gave only a narrow victory to Sen. Bob Packwood and cast 43 percent of their votes for an underfinanced, 35-year-old evangelical minister, Joe Lutz.

Even more startling -- though less well-publicized -- was the victory of two evangelical religious candidates in congressional primaries in Indiana. In both cases they beat candidates backed by the Indiana Republican Party, perhaps the strongest remaining political machine in the United States. And these were races that count: one is in a district where a Republican congressman is retiring, the other in a district where Republicans have targeted the Democratic incumbent.

Now comes a third test: the elections for Republican precinct delegate in Michigan. The delegates elected this August will get the presidential selection process started in January 1988, and Pat Robertson's Freedom Council has been urging those who believe in its values to get themselves on the ballot by filing petitions with 15 signatures by the May 27 deadline. Mr. Robertson (who also stumped for one of the successful candidates in Indiana) spoke to 4,000 enthusiasts in Detroit's Cobo Hall and, by electronic hookup, to 3,000 more in 10 places around the state. Since only about 10,000 precinct delegates will be elected statewide, that's a significant number.

No one knows how the Robertson people will do -- and no one will know for some time, since the precinct delegate filings are tabulated, old-style, by county clerks. But the results elsewhere so far suggest that opposition to abortion and support for what New Right leader Paul Weyrich has called "cultural conservatism" is wider and deeper than most Washington observers, Republican and otherwise, have thought.