Sacked on Saturday as Israel's minister of defence, Mr Yitzhak Mordechai last night made a bitter, blistering assault on the Prime Minister, Mr Benjamin Netanyahu, and pledged to lead a new centrist alliance to victory over Mr Netanyahu in May's general elections.
Mr Mordechai said the government had been steered astray by extremists and had abandoned peace-making, and he promised that, if elected prime minister, he would chart a course to "true peace" with the Palestinians.
Mr Mordechai (54) was sacked on national television by Mr Netanyahu on Saturday night for the "unprincipled" crime of negotiating with the centrists while still serving in the government.
The decision to dismiss him was an exercise in pre-emptive damage control, an attempt by the Prime minister to undermine the credibility and prestige of one of his closest former allies, who has now become his most dangerous political rival.
Yesterday morning, attending his final cabinet meeting as defence minister, Mr Mordechai bade farewell by reading ministers Psalm 120, including a quotation that runs: "Too long have I had my dwelling among those who hate peace. I am for peace, but when I speak, they are for war."
He underlined the sentiment in a speech last night, asking derisively: "Is there a dialogue with the Palestinians? Is there a [peace] process? Is there a way to advance agreements?" Under Mr Netanyahu's leadership, he said, what had been "a wonderful government" had lost its best ministers and its direction.
Mr Mordechai is the first defence minister ever to be sacked in Israel, and the fourth senior minister to leave Mr Netanyahu's government.
His departure further complicates Mr Netanyahu's efforts to secure re-election, and dramatically boosts the prospects of the new centrist alliance, where Mr Amnon Lipkin-Shahak has now stood down as likely leader in Mr Mordechai's favour.
Mr Netanyahu, Mr Mordechai and the Labour Party leader, Mr Ehud Barak, will now be the three key candidates in a wide-open race for the prime ministership, but Mr Barak and Mr Mordechai could eventually join forces, as they share the primary aim of ensuring Mr Netanyahu is not returned to power.
The significance of Mr Mordechai's departure lies in his Kurdistani origins, in his military record, and in his views on peacemaking. As the most successful representative of the Sephardi (North African and Middle Eastern) Jewish community in Israel, he brought swathes of Sephardi support to Mr Netanyahu's successful election campaign in 1996. As a former top general, he also gave Mr Netanyahu priceless credibility on security issues.
Now he takes both those qualities to the political centre, where misgivings over his Likud past will be offset for left-wing Israelis by his dovish attitude to the Palestinians and to regional peacemaking.
Several Palestinian leaders yesterday issued statements of support for Mr Mordechai. Mr Ziad Abu Ziad, a leading Palestinian politician, said Mr Mordechai's complaints about Mr Netanyahu as regarded peace-making were "well founded". And while Egypt's President Hosni Mubarak and Jordan's King Hussein had been intending to meet Mr Mordechai this week before he stepped down as a minister, neither head of state is prepared to meet any other member of Mr Netanyahu's government.
Mr Netanyahu was yesterday determinedly playing down the impact of Mr Mordechai's defection, and alleging that "personal ambitions" rather than principles were behind the move.
He claimed Mr Mordechai had sought a written guarantee that he would be defence minister in any subsequent Netanyahu government. Mr Mordechai denied this. A poll last night showed 45 per cent of Israelis believed Mr Mordechai; only 28 per cent believed their Prime Minister.
Today Mr Netanyahu is expected to be confirmed as the Likud's prime ministerial candidate in a party vote against his former mentor, Mr Moshe Arens. Somewhat bizarrely, Mr Arens (73) has indicated that if he is defeated, as expected, he will take Mr Mordechai's place as defence minister.