Last October, a group of senior federal employes in California was asked to attend a meeting at San Bernardino City Hall. Several said later that they thought they had been invited to hear a talk on personnel issues by Donald J. Devine, director of the Office of Personnel Management.

Instead, the gathering was a campaign rally for a conservative Republican congressional candidate -- with Devine the featured speaker.

A complaint was filed with the Merit Systems Protection Board, alleging that Devine's activity violated the Hatch Act, which bans partisan campaigning by civil servants. But because his job is exempt from the act, the matter was dropped.

Such political activities are at the heart of the controversy that has stalled Senate confirmation of Devine's nomination to a second term as head of the federal civil service.

Devine campaigned for at least 16 candidates in six states last fall, according to testimony at his confirmation hearings. Democrats on the Senate Governmental Affairs Committee, led by Sen. Thomas F. Eagleton (D-Mo.), contend that Devine has improperly politicized the civil service. They are solidly opposed to confirmation.

Democrats contend that in addition to his campaigning, Devine has expanded the number of political appointees at the Office of Personnel Management (OPM), has created a new level of top-ranked appointees and filled it with former Republican activists, and has used his office in other ways to benefit the GOP. Democrats acknowledge that Devine's activities are not illegal.

Devine and his Republican supporters said his activities are legal and proper under the 1978 Civil Service Reform Act, which abolished the Civil Service Commission and created the OPM, with a director appointed as an adviser to the president rather than as an independent commissioner.

The director's term is four years. Devine, 48, a former University of Maryland political scientist who was an early and ardent supporter of Ronald Reagan, is the first OPM director to be renominated.

Devine, who said he was not aware of complaints about his San Bernardino appearance, defends his political activities as a necessary part of Reagan's effort to shrink the size and improve the efficiency of government while limiting its intrusion into citizens' lives.

"I talk about the issues and why we need Republicans in Congress to help us," Devine said.

His campaigning also includes anti-Democratic rhetoric that upsets critics such as Sen. Paul S. Sarbanes (D-Md.). The senator quoted a speech, delivered last year in the congressional district of then-Rep. Donald J. Albosta (D-Mich.), in which Devine said: "Congressmen are like snowflakes. One or two don't make a difference, but a lot of bad ones are a problem. Unfortunately, you've got one here." Sarbanes called such partisanship by a civil service chief "a breach of responsibility."

Devine has aroused bitter opposition among federal employes because he is the principal architect of the Reagan administration's attempt to cut federal jobs and pay and to revamp rules determining how employes are promoted and fired. But his combative stance with Congress and his political activities seem to be the main reasons his job is in jeopardy.

The GOP, which has a 7-to-6 majority on the Governmental Affairs Committee, postponed the vote on Devine when it appeared he might lose. The vote is expected this month. The pivotal vote is Sen. Charles McC. Mathias Jr. (R-Md.), who reportedly is leaning toward opposition.

Almost all of Devine's 1984 campaign trips were combined with official OPM business, so that the bulk of the cost of Devine's travel and that of his OPM aides, who often were former Reagan campaign officials, was paid by the government, Eagleton said. Devine said he billed the government only for official OPM business.

Devine in 1982 created five "regional representative" jobs, paying about $45,000 a year and filled by former GOP operatives. "Their primary qualifications for their jobs appear to be their extensive Republican campaign experience," an Eagleton staff report said, noting that some OPM staff called the five "Devine's Commissars" and "Devine's Thought Police."

Devine scoffed at those characterizations and said the regional officials performed important public relations and congressional liaison tasks.