Campbell Expected to Quit Senate Seat Today : Politics: Sources say the veteran GOP legislator, who has been under attack, moved his planned resignation forward from January. He will become president of a trade group.

Sen. William Campbell (R-Hacienda Heights) has moved up his timetable to resign from the state Senate and intends to step down today instead of early next year, sources said Thursday.

Staff members serving Campbell’s office and his legislative committees were informed individually about the hastened departure Thursday. It was unclear what prompted Campbell to speed up his resignation.

The senator and his chief assistant, Jerome Haleva, were unavailable for comment Thursday. Senate sources said they had been told privately of the decision. Campbell, 54, shocked his colleagues in late October when he announced that he would leave elective office after 20 years to become president of the California Manufacturers Assn., a major trade group with extensive lobbying operations in Sacramento.

At that time, Campbell said he intended to stay on until early January, in part to finish up his legislative agenda and to pick the timing for a special election to replace him.

But his decision was lambasted by California Common Cause as a “serious conflict of interest,” and the public interest group criticized him last week for taking a “junket” when he led a handful of legislative colleagues to New York City to meet with bond houses.

Campbell, as chief of a joint legislative budget committee, scheduled as part of the official duties a tour of the Metropolitan Museum of Art. He and the legislators also paid calls on some corporate executives, who treated them to dinners, including one at the exclusive 21 Club, and free tickets to Broadway plays.

Atty. Gen. John K. Van de Kamp’s office is wrapping up a lengthy investigation into payments made to Campbell’s wife during a 1987 conference on women sponsored by the senator’s office.

The probe began in 1988 after newspaper articles disclosed that the 1987 event paid $165,000 in consulting fees to a firm owned by Margene Campbell and Karen L. Smith, a former aide who left Campbell’s staff earlier this year.

“I’m very optimistic that we’ll resolve the matter no later than the end of the year,” said Deputy Atty. Gen. Yeoryios Apallas, adding that he and his staff have examined more than 20,000 documents in the investigation.

When Campbell officially resigns, Gov. George Deukmejian has 14 days in which to call a special election to fill the Senate seat. The district covers the Orange County communities of El Toro, Brea, Placentia, Mission Viejo, Irvine, Yorba Linda, Lake Forest, Laguna Hills, Laguna Niguel and Silverado.