Sen. Joseph R. Biden Jr. (D-Del.) put it very well: It's a choice between arsenic and hemlock. Either the Comprehensive Test Ban Treaty is yanked out of Senate consideration for two years, or it is killed on the Senate floor next Tuesday.

"It's too soon," Sen. Pete Domenici (R-N.M.) was muttering to anyone who would listen in the Senate hallways outside the chamber.

Too soon? Forty years after Dwight Eisenhower proposed a ban, it is too soon to ratify a treaty negotiated in the term of another Republican president, George Bush? "Yes," he replied to astonished rejoinders. "It would go down, so it's the wrong time."

The Republican argument is advanced amid crocodile tears that the fate of the Earth must wait for another day. Majority Leader Trent Lott (Miss.) explains that in "another ten years or even two" the world situation may change or technology could be improved so that the U.S. Senate could see its way clear to curbing nuclear testing and keeping tabs on countries that insist on trying.

This is from the man who, having colluded with anti-treaty fanatic Jesse Helms in refusing for two years to have hearings or a vote, suddenly, out of the blue, demanded the ban be rushed to the floor on Oct. 12. The Democrats insisted on hearings, which were grudgingly acceded to as if the issue were nothing more momentous than changing daylight saving time. Lott also suggested he might be amenable to snatching the bill back from the burning that awaits it in the Senate chamber.

The fact that Lott, who loathes the idea of negotiating nukes with other countries, would consider a stay of execution, was supposed to make doves feel better. "It shows," said a Senate aide whose boss was being run over by a truck, "that he knows there's some opprobrium attached to opposing nuclear controls."

He is undismayed by the fact that some 82 percent of the American people are on the Democratic side of the issue. "It depends on how you ask the question," he claims.

Lott supposedly saw the wisdom of ramming the bill through the Senate after he heard from the Cold War mascot agency, the CIA, that certain low-yield atomic tests could not be definitively monitored. This information in a more rational precinct would have added to the urgency of passing the treaty, since that would guarantee on-site inspections at suspect location, which signatory nations are allowed to demand.

The CIA is revered by the know-nothings of the Senate. The agency may have missed the demise of the Soviet Union and gotten the address of the Chinese embassy in Belgrade wrong, but it thrills the reactionaries to be led up to the Senate attic and told secrets--like the one that low-yield explosions are hard to judge--that give them cover to vote against things they were going to vote against anyway.

Democrats, who are solidly for the treaty, complain about the absence of leadership from the White House. The president has thrown himself into the fight in the last week. Republicans such as Sen. Richard Lugar (R-Ind.), his party's most ardent internationalist, have withheld approval. Lugar complains that Clinton has not done the "education" needed for passage. Another Republican who disappointed doves is Sen. John Warner (R-Va.), who favors guns controls in other contexts. Only Sen. Jim Jeffords of Vermont and Sen. Arlen Specter of Pennsylvania had the valor to declare for the treaty.

Republicans of course deny that they are engineering an ignominious defeat for Clinton to blow a huge hole in his legacy. The treaty is more dangerous than proliferation, they insist. But they exceeded their reputation for truly epic pettiness this week by voting unanimously against the appointment of a black judge who was apparently insufficiently militant about the death penalty, although he confirmed 70 percent of the death penalties brought to him for review. It was a nasty business, as nasty as what they are doing on a cosmic scale on the treaty.

Byron Dorgan, the senator from North Dakota who led the drive for hearings and a vote, is one of the Democrats who want the issue brought to the floor. He thinks a roll call might flush out Republicans who are closet supporters, and who could not face their constituents if they voted wrong on curbing nuclear testing. Dorgan thinks the vote could focus the electorate's attention on the issue and identify the hawks. George W. Bush, despite his father's role, is among them.

Lott, who seems to hold all the cards, is asking a high price for yanking the bill out of the fire. Any reconsideration would be postponed until after the presidential election. The most immediate effect on the world scene could be in India, which along with its neighbor, Pakistan, recently exploded a bomb. India's prime minister, Atal Bihari Vajpayee, has declared his intention to sign the CTBT. His chances for ratification in the event of a Senate rejection would probably be annihilated.