Congress is getting ready to complete work on strengthening the Endangered Species Act, the worldwide standard for protecting plants and animals, after a four-year impasse was finally broken in the Senate.

The way was cleared Thursday when the Senate voted 93-2 for bipartisan legislation that would give the 15-year-old protection program more money and greater powers.The only "no" votes in the Senate were cast by Republicans Steve Symms of Idaho and Jake Garn of Utah.

The action capped four years of efforts by the bill's managers to bring the package to a floor vote. Until recently, they had been blocked by a handful of senators questioning efforts to protect sea turtles and reintroduce wolves to Yellowstone National Park.

Negotiators from the House and Senate now must meet to resolve relatively minor differences between the Senate's bill and one passed 399-16 by the House last December.

Technically, the endangered species program has been without legislative authorization since Oct. 1, 1985. The protection effort has been financed year by year since then, with some $39 million available this year.

The House and Senate bills would authorize $56 million next year, rising to $66 million in 1992.

The basic law, enacted in 1973, prohibits trade in species considered endangered or threatened and requires the government to take affirmative steps to foster their survival and take no actions that would hasten their demise.

There are now nearly 1,000 species on the Fish and Wildlife Service's endangered-threatened list, about 400 of them found in this country.

There are about 1,000 species awaiting formal listing. Sen. George Mitchell, D-Maine, floor manager of the Senate bill, said that at current spending levels it would take until 2020 to end this backlog.

Environmentalists say some 80 species have become extinct while awaiting listing and that another 300 may have passed the point of no return.

Both bills would increase the civil and criminal penalties for violations of the protection law and attempt to close a loophole that has allowed the destruction of endangered plants on private property.

The House passed a renewal bill in 1985, but it died because a handful of Westerners were able to keep the issue off the Senate floor. This year, Western opposition, centering on water rights and control of predators like wolves and grizzly bears, was muted.