For California Republicans: Reagan's a plus, Reaganomics is not

California's Republican candidates have what many observers say will be a fine line to walk this fall: how to be close to President Reagan - but not too close to Reaganomics.

The state's Republican contenders have worked hard to align themselves closely with the President for the upcoming June 8 primary, sometimes playing oneupmanship in their eagerness to appear as a Reagan favorite.

But as campaigns move into the general election - and as candidates work to broaden their appeal across partisan lines - many political pundits here predict that some Republicans may try to shield themselves from the fallout of public displeasure with the President's economic programs.

''The largest single effect on Republican statewide races will be how the public views Ronald Reagan,'' says pollster Mervin Field. ''A year ago it appeared that Republicans would have the edge. All they had to do was wrap themselves in the mantle of Ronald Reagan.

''Now,'' he warns, ''that mantle may be a smothering blanket. . . . The single biggest delicate problem for Republican campaign managers will be how to get succor from Ronald Reagan being President, but not be crushed by it.''

Mr. Reagan is still very popular in his home state. His ability to raise funds - the California GOP brought in a little more than $1 million at a May 25 dinner in his honor - is substantial. And among hard-core conservatives, loyalty to Reagan is considered such an important test that many Republican candidates have squabbled openly over who has the longest-standing record of support for Reagan.

In the Republican gubernatorial race, for example, Attorney General George Deukmejian and Lt. Gov. Mike Curb have worked hard in the GOP primary to show who has the longest track record of support for Reagan.

San Diego Mayor Pete Wilson, who just took the lead in California polls in the GOP race for the US Senate seat being vacated by Sen. S. I. Hayakawa (R), also has worked hard to show himself a close Reagan ally - an effort made more difficult by the fact that conservative Republicans remember that he campaigned for President Ford instead of Reagan in the 1976 presidential primary race.

''There's still a lot of love for Ronald Reagan, not only among the candidates but among the constituency.'' says William Campbell, state senate minority leader. ''In the Midwest and in the East, it may be a little different, but in California, Ronald Reagan will be welcome on any platform they can get him on.''

Despite this personal popularity, Reagan's job performance ratings have plummeted in California polls - from 64 percent in the state who rated him excellent or good in April 1981 to 37 percent this March. And the percentage of those who said they believed their household would be worse off as a result of Reaganomics rose from 36 percent last October to 51 percent in March.

''Sure it comes into strategy,'' says Bill Roberts, campaign manager for Mr. Deukmejian. In the general election, ''you want to be sure you're putting your best foot forward. You've got to be a little sensitive in how you handle it, but it's a decision . . . that will be made down the road a piece, in August or September.''

The economy - and Reagan's economic policies - already are being sounded as a major issue by Democratic candidates, particularly by Gov. Edmund G. Brown Jr., who also is running for Senator Hayakawa's seat. Criticism of Reaganomics has become an ideal political vehicle for Governor Brown, who reportedly is the Democrat the Reagan administration most wants to keep out of Washington, D.C.

However, California Republicans aren't expected to make any dramatic breaks with the President.

''It doesn't mean you'll see Republican nominees endorsing huge deficits or anything,'' Mr. Roberts says. ''But I don't think Republicans will be walking away from him.

Besides, notes Roberts and other Republicans, if the economy appears to be pulling out of its recession by this fall, and if unemployment begins to drop, the thrust of any Democratic attack on Reaganomics will be blunted.