A Senate Democratic task force set up in July to design a partywide economic program for the 1980s issued its report yesterday, basically endorsing what the White House -- and Senate Finance Committee -- already have proposed.

The 12-part document, intended as a response to the tax-cut plan proposed by Republican presidential candidate Ronald Reagan, was essentially campaign manifesto -- praising the Democrats' program and denouncing Reagan's as unsound.

Although the report called generally for tax cuts to promote investment and for new measures to revitalize American industry, there were no real specifics. The recommendations could have encompassed Carter's -- or any Democrat's -- plan.

Sen. Lloyd Bentsen (D-Texas), chairman of the panel, and a bevy of Democrats who took part in the preceedings issued statements endorsing the new plan. The Texan called the program "a framework" for economic policy over the next decade.

The 25-member task force was established by Senate Majority Leader Robert C. Byrd (D-W.Va.) after Reagan's repackaging of his earlier tax-cut plan last July sent Senate Democrats panicking and pushing for a tax cut of their own.

President Carter has vigorously opposed enactment of any tax reduction this year as likely to be inflationary. Many Senate Democrats found during the Labor Day recess that their constituents also were unenthusiastic about a cut.

Among the measures that the task force recommended yesterday were:

A tax cut in 1981, both to spur investment and to offset scheduled Social Security tax increases. The document alluded indirectly to Reagan's tax-cut plan as "simple-minded."

A "steady, long-term approach" both to budget and money-and-credit policies, along with dismissal of a Reagan-backed proposal that the United States return to the gold standard.

Establishment of a new Department of Trade to incorporate the trade-related functions now performed by the departments of State, Treasury and Commerce and other agencies.

Congressional observers said they expect few specific measures to result from the task force report. The report included an overview and statements by each of the panel's 11 subcommittees.