The Senate does agree on one thing - if it goes ahead, the vote on the Comprehensive Test-Ban Treaty (CTBT) will be the among the most important any of them will ever cast.

Mr Clinton's choice: Hemlock or arsenic?

However, although the US pushed for the CTBT and was the first to sign it, it seems unlikely to ratify it anytime soon.

The problem for the Clinton Administration is that it has to persuade some 22 Republicans to vote with Senate Democrats next week.

White House officials admit that they are about 15 votes short of the two-thirds majority required for treaty ratification, and there seems little chance that enough opponents will change their minds in the run-up to the vote.

Little middle ground

Supporters of the treaty say that it should be ratified, because it is verifiable; it stops other potential weapons states in their tracks, and won't affect the American nuclear arsenal.

Republican opponents say the treaty would not stop low level tests

Their Republican opponents, who refused to put the treaty forward for ratification for more than two years, say it is not verifiable, wouldn't stop secret low-level testing by rogue states, and could make the American arsenal impossible to maintain.

There is little middle ground.

What next?

The White House and Senators from the two parties are now engaged in intense negotiations about what should happen next. President Clinton would like the vote postponed for a few months to try to press his case and win over the waverers.

The Republican leadership has been hurt by the Administration's high-profile campaign in support of the treaty, and is well aware of the more than 80% public support for it.

They do not want to be swamped with negative publicity if they reject the treaty, and have offered to postpone the vote until after the next presidential elections.

But die-hard conservative opponents of the Treaty, like Senators Jesse Helms, James Inhofe and Tim Hutchinson, have said they are willing to force a vote next week, simply to ensure defeat for the treaty and the president.

The lesser of two evils

So the choice for the White House seems to be, as one Democratic Senator put it, between taking arsenic, or hemlock.

Either it tries to pull the treaty off the Senate floor until Mr Clinton leaves office, or it watches it go down in flames next week.