Mr Starr is due to appear today before the House of Representatives judiciary committee, to give his first public defence of his investigation into the Monica Lewinsky affair. His report, published in September, accused Mr Clinton of 11 impeachable offences, including perjury and obstruction of justice, and questions have been scheduled not just from committee members but also from White House lawyers. As preparations for Mr Starr's appearance were being completed, two developments guaranteed that today's hearing would be even more hostile than envisaged.
According to excerpts from his prepared testimony leaked to the media yesterday evening, Mr Starr will say that Mr Clinton of "misused his authority and power as President" to frustrate his investigation.
He will also charge that Mr Clinton "contravened his duty to faithfully execute the laws". Neither matter, says Mr Starr in the excerpts, is a private matter.
Mr Clinton has insisted that the relationship between himself and Monica Lewinsky, which was the subject of a grand jury investigation, was a private matter. "Even Presidents have private lives," he told a nationwide television audience after testifying under oath in August.
Just an hour earlier, the chairman of the House judiciary committee, Henry Hyde, had announced that his committee wanted to summon another four witnesses to give sworn evidence in addition to Mr Starr. They include Mr Clinton's adviser and deputy White House counsel, Bruce Lindsey, and the President's personal lawyer, Robert Bennett. The other two are concerned not with the Monica Lewinsky case, but with the case of Kathleen Willey, the White House volunteer who alleges that Mr Clinton groped her when she went to ask him for a job
The calling of additional witnesses has not yet been agreed by Democrats on the judiciary committee and may have to be put to a vote today or next week. That two of the additional witnesses are not connected to the Lewinsky case also suggests that Mr Hyde intends his committee's hearings to range more widely. Until yesterday, Kenneth Starr had been the only witness called - in order, it was said, to ensure the hearings were completed rapidly.
The new developments only increased the tension in advance of today's impeachment hearings, which were instituted last month after Mr Starr presented his report to the House of Representatives. The hearings, which are only the third of their kind in US history and the second this century, place Bill Clinton in a class with Andrew Johnson, whose impeachment was voted down by the Senate, and Richard Nixon, who resigned before proceedings entered their final stage.
The Starr report accused the President of 11 "impeachable" offences, including perjury and obstruction of justice.
Preparations for the hearings were marked by acrimony from the start, with Democrats accusing Mr Starr of partisanship and Republicans of aiming to oust Mr Clinton by fair means or foul. The outcome of this month's mid-term Congressional elections, which brought Republicans unexpected losses, embittered the process further as Democrats cited the "will of the people" and called for the hearings to be abandoned, and Republicans insisted that the Constitution required them to proceed.
There was also much grumbling from Democrats about the timing of the release of tape-recorded conversations between Linda Tripp and Monica Lewinsky. The tapes, transcripts of which have been available for six weeks, were released on Tuesday, reviving all the sordid details of the Clinton-Lewinsky relationship.
Yesterday, the White House finally accepted the 30 minutes originally offered by the committee chairman, Henry Hyde, dropping the demand for at least 90 minutes. But they masked their concession with angry words. Speaking as Mr Clinton set off for a visit to Japan and Korea - curtailed by last weekend's crisis over Iraq - the White House spokesman, Joe Lockhart, accused the Republicans of "walking in lock-step" with Mr Starr and added: "There is something fundamentally unfair and disturbing about the Republicans and the independent counsel saying that they can cover any subject they want, they can expand this into any fishing expedition they want, but the President's counsel has to keep on the issues that they think are germane."