To the delight of Republicans and discomfort of some Democrats, Jerry Brown is back in the political spotlight, campaigning for the once-obscure post of chair of the California Democratic Party.

The political comeback of the former governor and two-time presidential candidate follows six years of self-imposed political exile - part of it spent in seclusion writing in Mexico and Japan and part working in Mother Teresa's hospital in Calcutta and on a CARE hunger project in Bangladesh.Brown's latest campaign will conclude with voting Saturday among the 2,800 delegates credentialed for the California Democratic Party's annual convention.

Brown, 50, once dubbed "Gov. Moonbeam" by his critics, has lined up endorsements from an impressive array of party leaders and is regarded as the favorite over investment banker Steve Westly, 32, of Menlo Park. Westly is the current vice chair of the party and traditionally would be unopposed for chairman.

Brown's critics note that as governor from 1975 through 1983, he shunned the party, and they contend he would use the chair's office not to serve the party but as a stepping stone to advance his own political career.

They also say one of his weaknesses as governor was neglect of the sort of administrative detail that is a major part of the state chair's job, and that Brown's election would give new life to what have become stale Republican attacks against controversial aspects of Brown's governorship.