There is no definite constitutional roadmap for the process, the last such impeachment trial having been held 130 years ago. But having embarked on the largely uncharted course, lawmakers and analysts are invoking metaphors likening the process to a runaway train or a bus hurtling towards a cliff to describe the unknown end.

Some of the procedural aspects of the trial began to emerge slowly just hours before the trial. Here's what will happen: The US House of Representatives, which impeached Clinton in December, will convene on Wednesday to re-endorse the 13 members they elected to be `Floor Managers,' a group which will function as the prosecution team in the Senate and represent the people of the United States.

The Floor Managers will be escorted into the Senate chamber to a specially constructed table in the well of the chamber. They will read thearticles of impeachment charging Clinton with lying under oath and obstructing justice to conceal his affair with Monica Lewinsky. The Senate will formally notify the Chief Justice of the Supreme Court, William Rehnquist, that it is ready to proceed.

Chief Justice Rehnquist will come to the Senate at 1 p.m. on Thursday and will be sworn in by the presiding officer, who in normal circumstances for such important occasions, would be vice-president Al Gore. The Chief Justice in turn will administer a special oath to the 100 Senators who will be the silent jury while the prosecution conducts its case. President Clinton will be summoned, but he need not be present in person. He will be represented by his legal team.

At this point, the aims and objectives of the lawmakers diverge. It is common knowledge despite a 55:45 advantage in the Senate, the Republicans still cannot muster the two-thirds vote (67) needed to convict Clinton and remove him from office. But because the House has embarked on what it says is aconstitutionally mandated path, the Senate -- Republicans and Democrats -- is willing to listen to the case briefly and set it all aside after a quick vote, or a censure.

The Senate is said to be the less partisan bodies of the two and so it seemed when Republican leadership of the chamber floated ideas for a brief, abbreviated trial. But the proposal was shot down by a few Republican hard-liners in both the House and the Senate with the moderates unable or unwilling to exert their influence.

The conservatives also rejected proposals for an early `test vote' to see if a two-thirds vote was possible. The Republican prosecution team led by Congressman Henry Hyde want a full-blown trial, complete with witnesses like Monica Lewinsky.

So as things stand, all bets are off about the President's fate. Although the Republicans do not have the votes needed to convict Clinton, they hope to go the whole length, a process fraught with unknown consequences. Given that no one thought last year that even theimpeachment was a possibility, pundits are cautioning against predicting anything. ``Be careful, be careful,'' warned Democratic Senator Robert Byrd, a nonpartisan lawmaker who is the Senate's constitutional beacon. ``There is no sound and indisputable count as to the votes here. And votes may shift depending on things that are unforeseen at the present. Who knows? This could conceivably end differently.''

One of the unforeseen scenarios could involve a Arkansas hooker who is now going around claiming that Clinton fathered her child when he was Governor of Arkansas. The White House has studiously ignored the story, now slowly trickling into the mainstream media, but Clinton-haters are fueling the story and hoping it will consume the trial process. It now looks certain that the trial will go on not just for days, but even weeks and months.