With the administration under siege on several fronts, there is strong speculation that the investigation could lead to the indictment of top advisers to President George Bush and Vice-President Dick Cheney, and possibly other senior officials as well.
All eyes were fastened on the District of Colombia federal courthouse on Pennsylvania Avenue where the 23-member grand jury investigating the case was meeting. A small army of TV crews and reporters waited for a Washington scandal's equivalent of white or black smoke to issue from the legal chimney.
By early afternoon, the colour seemed to be a murky shade of grey. Mr Fitzgerald is understood to have presented the conclusions of his two years of labours at a three-hour session, before the jury adjourned for the day.
Assuming that is so, jurors have to decide by simple majority whether he has made enough of a case to warrant whatever indictments he is seeking. This step is considered unlikely before tomorrow, when the jury's term expires.
Proceedings have been so shrouded in secrecy that for once, even Washington's most loquacious insiders confess they do not know what will happen. Even at this 11th hour, Mr Fitzgerald could ask for an extension of his inquiry - or even not seek any indictments. But the firm betting last night was that he would issue charges, today or tomorrow.
The investigation into who leaked the name of CIA operative Valerie Plame to the media has zeroed two of the administrations most powerful officials, Karl Rove, the White House deputy chief of staff, and Lewis "Scooter" Libby, chief of staff to Vice-President Cheney.
Two sets of charges are possible: one involving the leak itself, a criminal offence under US law, the other covering perjury or obstruction of justice arising from discrepancies in the grand jury testimony of the two aides.
For days, television cameras have been encamped outside Mr Rove's and Mr Libby's homes. Their every public movement is monitored, while pundits wonder whether they have been notified of indictment - even whether they are quietly negotiating plea bargains with Mr Fitzgerald.
Gamely, the White House is maintaining a pretence of business as usual, "focused on the issues that Americans care about", in the words of Scott McClellan, Mr Bush's spokesman. Mr Libby is on crutches after breaking a bone in his foot, but Mr Rove yesterday managed a smile to reporters, and jokingly saluted a passing colleague.
Mr Bush's own schedule was fairly typical: a meeting with Zalmay Khalilzad, the US ambassador to Iraq, a session with lawmakers followed by a speech to the Economic Club of Washington. He also held talks with the Macedonian Prime Minister.
"Leak-gate" is not another Watergate in the sense that, as far can be seen, neither Mr Bush nor Mr Cheney is directly in the line of fire. But for the administration, the stakes are enormous.
On Capitol Hill separate trouble seemed to be brewing, this time over the President's Supreme Court nominee, Harriet Miers. Her withdrawal would be a huge embarrassment - but in the past few days it has started to look a distinct possibility.
Officially, the President is standing behind Ms Miers, the White House counsel for the past 10 months, whose confirmation hearings before the Senate Judiciary Committee is to start on 7 November. But, amid accusations of cronyism, almost a dozen Republican senators have expressed doubts about the nominee, while several leading conservatives have publicly urged Mr Bush to come up with a better-qualified candidate.
The top Republican and the top Democrat on the committee last week sent back Ms Miers's response to a questionnaire about her legal career and views, saying it was inadequate and incomplete. And yesterday there were demonstrations outside the White House by anti-war protesters as the number of US troops killed in Iraq passed 2,000.
But the greatest danger lies in the leak affair. An indictment would force Mr Rove to step down, depriving Mr Bush of his ablest adviser. Word is that the White House has lined up Ed Gillespie, the former Republican Party chairman, as a temporary replacement. If Mr Libby is charged, it would be a body blow to the most influential vice-president of modern times. But the leak investigation has become a metaphor for the alleged manipulation of intelligence to make the case for military action.
Meanwhile, The Wall Street Journal reported yesterday that Judith Miller, the reporter who was jailed for 85 days for refusing to reveal her sources, is to leaveThe New York Times.
Three issues that put president under pressure
THE CIA LEAK
The accusers say CIA officer Valerie Plame was outed by senior White House staff after her husband Joseph Wilson refused to help build a case for the Iraq war. US envoy Wilson visited Niger and found claims Iraq was attempting to buy enriched uranium were "baseless". When no one listened, he went public in The New York Times. Within a week his wife's CIA status was revealed in the right-wing media.
THE NOMINATION OF HARRIET MIERS
President Bush's second pick in as many months for the Supreme Court has run into angry opposition even from his own party. Choosing Miers, previously his personal lawyer, has opened Mr Bush up to attacks of cronyism. Conservatives have loudly questioned her constitutional expertise, leaving her confirmation in serious doubt.
Not even a "yes" vote for the much-touted constitution on Tuesday could turn the grim tidings on Iraq. The White House spent the day marking the 2,000th US troop death, and the President warned an increasingly hostile public more sacrifices would have to be made.Reuse content