WASHINGTON (AP) _ The Energy Department is proposing steep cuts in federal winterization programs for the poor and environmental cleanup at weapons plants to comply with White House orders to reduce spending, government sources said Wednesday.

The department spending proposal for the next fiscal year also includes closing one of the government's prestigious research laboratories and less money for fusion research at Princeton University, though the program is expected to survive, the sources said.

Only a broad outline of the spending cuts were provided by administration officials, who spoke on the condition that they not be identified further. In all, the cutbacks were to save $10.2 billion over five years, the sources said.

The proposals were in addition to plans, disclosed earlier, for selling off four of the government's power marketing agencies that produce wholesale electricity in much of the South and West. That sale was estimated by the department to save $12 billion over five years, but government and private energy experts say the four agencies probably aren't worth that much.

The Tennessee Valley Authority is not included in the sell-off, officials said.

The budget reductions proposed for the fiscal 1996 budget that begins next October are part of an administration-wide effort to curtail the size of government in response to congressional Republicans' push for the same.

The key proposals advanced by Energy Secretary Hazel O'Leary, with savings over a five-year period, include:

-Turning over to the states federal winterization programs that subsidize the poor in buying insulation and making other improvements to make their homes more energy efficient, saving $1 billion over five years.

-Cutting environmental cleanup and restoration programs at federal weapons plants, saving $4 billion. The government is spending about $6 billion this year on the cleanups.

-Cutting basic science programs, including closing one of the major government research labs, saving a total of $3.6 billion. Although no determination has been made which facility would be shut down, a task force for months has been examining whether all three major weapons labs - Los Alamos and Sandia in New Mexico and Livermore in California and - are needed.

-Privatizing the Naval Petroleum Reserve, saving $1.6 billion.

Some of these cuts are surely to be opposed in Congress when Clinton submits his budget next year. The proposed sale of the government power authorities, including the Bonneville Power Administration in the Northwest, already was attacked Wednesday by both Democratic and Republican lawmakers from the West.

''Any proposal to sell Bonneville is preposterous on its face and downright menacing,'' said Sen. Mark Hatfield, R-Ore., chairman of the Senate Appropriations Committee.

Rep. Pete DeFazio, D-Ore., called the idea a ''politically inspired shell game'' and said it could spawn electricity rate increases of 20 percent in the Pacific Northwest.

The proposal anticipates that the sale of the Bonneville would generate $6 billion. Selling the four other regional agencies - Southwestern Power, Western Area Power, Alaska Power and Southeastern Power - would generate another $6 billion.

The suggestion that selling Bonneville could net the government $6 billion ''is just laughable'' considering the agencies large debt and its environmental problems in protecting the salmon, said Rep. Norm Dicks, D-Wash.

The American Public Power Association in a letter to Clinton expressed concern about selling the power agencies' assets ''at a fire sale'' and losing ''a major asset capable of creating a continuing cash flow.''

''This is like a homeowner selling his house for the unpaid portion of the mortgage,'' wrote Larry Hobart, executive director of the APPA, which represents publicly owned utilities.