Led by the White House chief counsel, Charles Ruff, who presented the opening statement, the team set out to dissect and discredit the small- print of the charges.
But the most effective advocate for Mr Clinton yesterday was expected to be the President himself.
His State of the Union address last night gave him a unique forum to argue why he should remain in office. Without mentioning the "I-word", he was expected to lay out the case against his removal.
And with his job-approval ratings as high as Ronald Reagan's at their peak and more than 80 per cent of Americans - according to a CNN/USA Today poll - pronouncing his presidency successful, public support is still Mr Clinton's strongest suit.
The difficulty his defence team faced was to persuade the Senate of the legal, rather than emotional, case for keeping him. They had also to address specific points: that lying about sex under oath was the same as lying about anything else under oath and that by trying to keep his relationship with Monica Lewinsky out of court he was depriving Paula Jones of her constitutionally guaranteed recourse to justice in her sexual harassment suit.
Over the weekend the White House lawyers signalled that initially at least they would seek to contest the accuracy of the charges, arguing not that lying about sex was too trivial to justify impeachment but that the charges of perjury and obstruction of justice could not be substantiated.
Yesterday the White House indicated it also intended to bolster the political arguments. As well as unexpectedly calling on three Democratic members of the House of Representatives to plead Mr Clinton's case later this week, they also co-opted Dale Bumpers.
Mr Bumpers, who retired from the Senate last year, is a Democrat from Mr Clinton's home state of Arkansas. He is also a Senate diplomat whose word carries weight on both sides of the chamber.
The White House decision to pay as much attention to politics as to law, to persuading the Senate of the political risks of removing the President as well as what they argue are the legal defects of the prosecution case, reflects a twofold concern.
The Clinton camp, it is said, was taken aback by the strength of the prosecutors' presentation, and worried that it has lost the argument over calling witnesses. If politics can trump the law in a constitutional process that meshes the two, the President has won. If not, the odds are more even.Reuse content