The Chief Justice of the Supreme Court, William Rehnquist, will be summoned at 1pm to take the oath and swear in the Senators. With a terse announcement to that effect, the leader of the Republican majority in the Senate, Trent Lott, established that the impeachment trial of a President - only the second in history - would actually commence.
While a trial is now inevitable, a "full trial" even, as noted by Mr Lott, a continuous series of meetings through yesterday within party groupings and between Senate and House leaders still yielded no agreement on what form the trial would take.
Indeed, while a new mood of reconciliation prevailed in the House of Representatives, the Senate appeared to have inherited all the quarrelsome ill-temper of the last House - along with the responsibility of dealing with a philandering, and possibly perjurious, President.
The new atmosphere of cooperation in the House of Representatives was set by theSpeaker, the Illinois Republican Dennis Hastert, who took over the gavel from Newt Gingrich, and was immediately welcomed by his Democrat counterpart, Dick Gephardt, with a call to "bury the hatchet". Mr Hastert readily responded, choosing to deliver his acceptance speech from the floor of the House, rather than from the Speaker's chair, to illustrate that his "home" was on the House floor and his "heart" with the rank and file legislators.
In the Senate, however, once the 34 new Senators had been sworn in, the mood was fractious and uncertain.
Through the day, Mr Lott had expressed optimism that he and the leader of the Democrat minority, Tom Daschle, would reach agreement on procedures and a timeframe for the trial. By the end of the day, and many meetings later, Mr Lott admitted that although the list of questions was being "narrowed", "there are a lot of gaps". Unconfirmed reports indicated that opening statements, effectively the real start of the trial, might not be heard until the middle of next week.
A strong body of opinion among Republican Senators continued to insist that a trial is not a trial unless witnesses are called and questioned so that the Senate, which constitutes the jury in an impeachment trial, can make up its own mind about the merits of the case. That determination appeared to strengthen through the day, following the convening of the full Senate for the first time since October, and by evening there were unconfirmed reports that a list of witnesses was already being drawn up.
Outside the Capitol there was minimal sense of drama and still less public concern, given that the US was on the eve of a trial that just might remove the country's 42nd president. The White House, which appeared to have abandoned all hope of preventing a trial, tried to sound a note of confidence. The spokesman, Joe Lockhart, said: "Based on the facts and based on the Constitution, the President will prevail."
White House officials had earlier made known that Mr Clinton's lawyers were preparing for an aggressive defence of the President in the event of a trial, including challenges to the substance of the two charges against him: perjury and obstruction of justice over his attempts to conceal his affair with Monica Lewinsky.
As his lawyers do not know what form the trial will take, they are having to prepare for any eventuality, including the calling of White House staff as witnesses.
In the past two weeks, Mr Clinton has stuck to what he calls "the nation's business", announcing generous spending proposals that could find their way into this year's budget and capping the optimism yesterday with his announcement of a projected $76bn domestic budget surplus for 1999.