Rep. Barry M. Goldwater Jr. (R-Calif.) has lost his long-held position as front-runner for the Republican nomination in the U.S. Senate campaign in California, according to a poll released today.

The survey, conducted May 22 and 23 by Teichner and Associates, shows San Diego Mayor Pete Wilson in the lead with 26 percent, Rep. Paul N. (Pete) McCloskey with 20 percent and Goldwater with 19 percent.

When undecided voters were urged to make a choice, Wilson led with 30 percent, Goldwater was second with 23 and McCloskey with 22 percent. The poll's margin of error is 4.5 percent.

The 19 percent figure for Goldwater represents a loss of 5.4 points from the previous Teichner poll, taken May 1 and 2.

Wilson campaign aide Otto Bos said, "We seem to be peaking at the right time. I think Goldwater Jr. is paying the price for not debating and being very bad in his attendance rating. It looks like, going into the stretch run, we're overtaking him."

Bos said Wilson's polls had shown the change, but that Wilson's staff has refrained from commenting until those results has been confirmed by another poll.

Goldwater has been criticized for running a low-profile, sometimes almost invisible, campaign in which he refused to debate his opponents. Goldwater also failed to make a number of joint appearances with several of the other 13 candidates in the race, including President Reagan's daughter, Maureen, and Rep. Robert K. Dornan (R-Calif.).

Goldwater's campaign manager, Ben D. Key, said he doubts the credibility of any poll that shows "two liberal candidates McCloskey and Wilson getting 46 percent of the vote in a California Republican primary."

When Goldwater does make an appearance he often seems ill at ease, and his penchant for malapropisms has fueled comments by his opponents and the press that he may be a poor debating foe for Gov. Edmund G. (Jerry) Brown Jr.

Brown, who has also refused to debate his primary opponents, is virtually guaranteed the Democratic senatorial nomination. Both Wilson and McCloskey have advertised themselves as the Republicans best able to beat him.

Brown's campaign chairman, Mickey Kantor, said today in response to the poll that, "It's our view that any Republican nominee is going to have to defend his position on the economy. Each one of them has supported the policy which has resulted in high umemployment, high interest rates, a record deficit and a nearly unparalleled number of bankruptcies."