General Services Administration chief Gerald P. Carmen said this week that he'll probably resign in October unless President Reagan once again persuades him to stay longer.

"Last October I tried to leave and he asked me to stay for another year," Carmen said. But he refused to confirm or deny that he was headed for a Reagan reelection campaign. In 1980 Carmen, then a New Hampshire auto parts wholesaler and Republican state chairman, was New England coordinator for Reagan. Over the past year he has often said he misses "pure politics."

"It's a fun job, but it's a pain," Carmen said of his current job. "I think the president has done a very fine, creditable job and will enjoy the support of the people if he can avoid getting us involved in some unfortunate foreign situation."

Carmen has developed broad support at the GSA for sweeping changes designed to make the agency run more like a business, yet he has also called for openness and accountability. A few outspoken critics, such as whistle blower Bertrand G. Berube, contend, however, that Carmen cut GSA's budget deeper than the Office of Management and Budget had asked, and in the wrong places.

Some of Carmen's ambitious legislative agenda may be in place before he leaves. Measures pending on Capitol Hill would change the cumbersome system of reimbursing employes for work-related travel, revise the way federal employes are reimbursed for relocation expenses when they are transferred and start requiring agencies that buy through the GSA's supply system to pay the full costs of their purchases, including transportation and warehousing. The GSA now has to bear those costs.

ON THE HOME FRONT. . . Although the GSA is supposed to be squeezing federal workers into an average of 135 square feet of office space apiece, federal employes in Carmen's home town almost got to keep much more spacious digs. A planned renovation of a Manchester, N.H., federal building, now awaiting congressional approval, would have given employes more than 300 square feet each.

The plan was first approved before President Reagan issued an executive order mandating the space reduction, but top agency officials signed off on it again this May, after the reduction plan was in place.

"It wasn't wrong when we drew it up, but it should now be changed," said Public Buildings Commissioner Richard O. Haase. Haase said every renovation plan now sent to Capitol Hill for approval would have the space-cut requirement written into it.

WORK-PLACE SAFETY. . . Fears that the GSA isn't moving quickly enough to protect employes from carcinogenic airborne asbestos in the Star and Safeway buildings on Pennsylvania Avenue NW has forced the professional association of the Justice Department's Antitrust Division to take its complaints to Deputy Attorney General Edward C. Schmults.

Association President Laura Ross Blumenfeld said a study by Dr. Morton Corn, a former head of the Occupational Safety and Health Administration and now chairman of the Center for Occupational and Environmental Health at Johns Hopkins University, demonstrated that the asbestos situation required "action now."

James G. Whitlock, the regional public buildings commissioner, said that a new "action plan" is now in place to monitor all renovation work and that the GSA will continue to sample the air in the buildings.