Budget officials at 34 agencies, already wrestling with proposed spending cuts for fiscal 1986, are discovering unhappily that the Office of Management and Budget is serious about complying with a congressional request to cut more than $3 billion from their current administrative budgets.

A Senate amendment to last summer's Deficit Reduction Act deputized OMB to seek reductions in federal travel, consultant fees and publishing, public affairs and motor vehicle costs, areas of potential savings targeted in the report of the President's Private Sector Survey on Cost Control, commonly known as the Grace Commission.

The amendment's sponsor, Sen. Dennis DeConcini (D-Ariz.), is openly skeptical of the administration's chances of realizing even one-third of the requested savings. "If I saw a billion dollars actual real savings . . . , I would consider that exceptionally good. But I don't see it," he said.

"It boils down to the OMB director and the president himself saying that we've got to do it," DeConcini added. "If they're not prepared to do that, I can't sue them . . . . All I can do is put the legislation in again, tougher and stronger."

But, at least as far as domestic-agency budget officials are concerned, OMB seems prepared and eager to carry out Congress' wish.

As one agency budget official said yesterday, "In this particular year, when you have a huge deficit, anything you can do that seems easier than going after the programs themselves will probably occur."

"We're taking this very seriously," said OMB spokesman Edwin L. Dale Jr., whose agency sent out a detailed bulletin Nov. 8, telling each of the agencies how much to cut from the various accounts.

OMB interpreted DeConcini's amendment to mean cuts of: $1.031 billion in travel and transportation expenses, 15 percent. $1.401 billion in consulting services, 31 percent. $63 million in public affairs and advertising expenses, 37 percent. $347 million in printing and publications, 26 percent. $162 million in motor-vehicle maintenance and operation, 24 percent.

The General Services Administration, which controls 90,000 motor vehicles -- more than any other civilian agency -- was asked to cut $30 million from its budget for operating and maintaining those cars and trucks.

In the motor-vehicle category, and most of the others, DOD is the big spender; two-thirds of the $3 billion in requested cuts would come out of the Pentagon's budget. But OMB officials say privately that they don't believe that DOD will make the cuts.

"We're giving that document . . . , appropriate consideration," said Jim Turner, a DOD spokesman.

On the domestic side, however, budget officials were considerably more voluble about the potential effects of the cuts. "If you want the inspector general to do his job, his people have to travel," said one official.

Officials at the Interior and Agriculture departments have noted that managing their vast landholdings -- the national forests in USDA's case, the national parks and wilderness areas in Interior's -- requires extensive use of motor vehicles.

At the Energy Department, spokesman Phil Keif said, "Our people are pretty straightforward; they'll do their best" to make the cuts. However, he indicated that a recent reduction-in-force had trimmed the staff of the public affairs office and that further public affairs cuts seemed unwarranted. "We've appealed some of those cuts and are in active negotiations with OMB," Keif said.

"We're going to respond and haggle with OMB about this . . . , " said Treasury Department spokesman Bob Levine. Agriculture Deputy Secretary Richard E. Lyng said, "We aren't going to give OMB nothing but words, but we can't give them everything they want."

Because of the law prohibiting the executive branch from impounding or refusing to spend congressionally authorized funds, the agencies' cuts must be submitted to Congress for approval.