The Hatch Act should not be changed or repealed, President Reagan affirmed to Congress in the legislative message accompanying his State of the Union address.

In setting out the centerpieces of his civil service agenda for his last year in office, Reagan also announced in the 39-page document that he would implement government-wide random drug testing and would step up efforts to contract out work to the private sector.

On the Hatch Act, Reagan said proposals to amend the act, which bans most partisan political activities by federal workers, would "politicize the civil service and reduce public faith in government."

The House last year approved legislation allowing federal workers to run for public office, raise money or participate in the management of a political party on their own time. The Senate is expected to hold hearings on the bill next month.

Opposition to Hatch Act revision has been building in recent weeks after the bill sailed through the House with bipartisan support. Constance Horner, head of the Office of Personnel Management, said momentum for amending the act has slowed, spurred by recent opposition from the National Academy of Public Administration, the Senior Executive Association, the Federal Executive Institute Alumni and Common Cause.

She said it is "very difficult to tell" how Hatch Act revision will fare in the Senate.

Reagan earlier threatened to veto Hatch Act amendments sponsored by Rep. William Clay (D-Mo.), but Clay remains optimistic about the bill's chances, aides said.

Robert Tobias, president of the National Treasury Employees Union, said the president was "fearmongering" -- presenting a frightening picture of a politicized work force.

On the issue of testing for illegal drugs, Reagan said that "agency programs that include random testing to identify . . . drug users will be ready for implementation in 1988."

Under a compromise with Congress, the administration promised to send its plans for random testing of employees in sensitive positions to Capitol Hill for comment before any new testing programs begin.

The Department of Health and Human Services is within two to three weeks of completing final technical and scientific guidelines for the tests, and the program is expected to be submitted to Congress soon after, according to OPM.

Employees must be given 60 days' notice before testing can begin, and individual employees subject to random testing must be given 30 days' warning.

Two agencies sent out the 60-day notices last fall -- OPM and the Veterans Administration. However, both currently plan to send new notices before the random testing begins, according to the Interagency Coordinating Group handling the issue.

OPM says testing is likely to begin "in the spring." Andrea L. Nelson, counsel to the House civil service subcommittee, said testing may begin "mid-March at the earliest."

In the written message, the president favorably noted OPM's proposal to offer federal workers the option of purchasing nursing home or home health-care insurance. This proposal has languished in Congress for three months.

Horner said that the long-term care bill, sponsored by Sen. Pete Wilson (R-Calif.), has been delayed while Congress "got catastrophic health insurance off its platter." She said there is a broad consensus for offering the optional insurance.

The bill would give federal workers choices of different levels and costs of long-term insurance.

Dixon Arnett, Wilson's legislative director, said the senator has asked for hearings "as soon as possible."

The president, in his message, reiterated his commitment to the privatization of government operations where "opportunities exist to provide better services at lower cost."

"This does not imply the abrogation of government responsibility for these services," the president said. "Rather it merely recognizes that what matters the most is the cost and quality of the service provided, not who provides it. In addition, there is an important moral consideration -- individual liberty would be enhanced and the debilitating effect of public sector growth on human freedom would be reduced."