The White House sent a crack team of lawyers and constitutional experts to Capitol Hill to tackle the charges against him head-on for the first time. It also issued a 200-page riposte to the report compiled by the independent prosecutor, Kenneth Starr, arguing that, while Mr Clinton's conduct in the Monica Lewinsky affair was "sinful", it was not impeachable. There was a glimmer of good news for the White House, too, in the announcement that a senior Republican, William Weld, had agreed to testify today on the President's behalf. The former governor of Massachusetts, he resigned last year to pursue his (unsuccessful) nomination as ambassador to Mexico. His testimony marks the first open split in Republican ranks since the Judiciary Committee began formal impeachment hearings and could be crucial in persuading moderate Republicans to vote against impeachment. They are seen as the "swing" voters in an otherwise hung House.
The President's defence before the House committee was led by Gregory Craig, recently appointed White House special counsel. Adopting a more apologetic tone than Mr Clinton's other representatives, he began with what could have been interpreted as a small olive branch: "The President wants everyone to know - the committee, the Congress and the country, that he is genuinely sorry for the pain and damage that he has caused."
But he was adamant that while Mr Clinton's conduct was "morally wrong", it was not illegal. Of the perjury charge - that Mr Clinton repeatedly lied under oath about the nature of his relationship with Ms Lewinsky - he insisted evidence as it stood "could not sustain a criminal prosecution, much less impeachment". To be sure, Mr Clinton's evidence under oath was "evasive, incomplete, misleading, even maddening", he said, "but it was not perjury".
Mr Craig and the nine expert witnesses called through the day's session made much of the "personal" nature of Mr Clinton's misconduct and what they said was his motive - to conceal the affair from his family and the public, rather than to mislead the courts.
They also sought to demolish parallels with the Watergate scandal. Wayne Owens, a Democratic Representative at the time of Watergate, said Richard Nixon "used his executive powers to interfere with course of justice and conceal proof of his subordinates' conduct"; Mr Clinton, by contrast, was trying to conceal "an illicit sexual affair ... for his own and his family's sake".
The role of impeachment, said former Representative Elizabeth Holtzman, was "to protect the country, not punish the President".
A clear purpose of the revised defence tactics and the dossier released by the White House yesterday evening was to return the hitherto partisan debate to strictly legal points and counter the impression of arrogance created by Mr Clinton's legalistic written responses to the committee's 81 questions. The dossier, for instance, accuses Mr Starr of deliberately disregarding statements by Ms Lewinsky and others that contradicted his view of a president trying to obstruct the judicial process.
And it repeatedly cites Ms Lewinsky's closing remark to the grand jury: "No one told me to lie and no one promised me a job for my silence." (Mr Starr's response to that before the committee was that no one needed to tell her to lie, because she already had a tacit agreement with the President.)
The evidence piled up by the White House yesterday was thought unlikely to discourage the committee from approving articles of impeachment - formal charges - against Mr Clinton. Its main target was seen as members of the House of Representatives still undecided about which way to vote.