He was surrounded by his most trusted advisers, including his press spokesman, Ricardo Franco Levi, and few doubted his determination to resist a new set of terms from the European Parliament. One ally said: "His attitude was: 'Let's get this straight, rather than agree to this or I am going straight back to Bologna.'"
Less than six months after the implosion of Jacques Santer's discredited Commission, Europe has returned from the brink of another, potentially bigger crisis. The occasion was a set of hearings by committees of the Parliament to approve the 19 nominated commissioners. The catalyst was a phone conversation on Wednesday between Mr Prodi and the leader of the largest group in the Parliament, Hans-Gert Pottering.
The previous day, surrounded by journalists, Mr Pottering suggested that Mr Prodi's team should face not one but two votes. The first would come as planned on 15 September but the second would be in December or January, until which time the Commission would effectively be on probation. Mr Prodi registered his anger with Mr Pottering in a phone call in which the latter refused to give ground. Almost immediately, Mr Prodi and Mr Levi began drafting the statement.
MEPs were outraged at the ultimatum, but Mr Pottering's centre-right bloc soon back-tracked, dropping its double-vote threat and instead calling for concessions to boost the Parliament's role. Celebrations in Mr Prodi's camp continued when Pascal Lamy, the Frenchman nominated as Trade Commissioner, escaped an expected barrage of criticism as centre-right MEPs pulled their punches.
So, did three days of frenzy reveal anything significant? The events are part of a power struggle between a newly self-confident Parliament and a badly damaged Commission. Having forced the sacking of the last Commission in March, the Parliament is on a roll. This is also one of the few occasions when it has clear leverage. The incoming commissioners face a three-hour grilling before a vote on the suitability of the entire Commission. Yet MEPs cannot vote to veto individual candidates and the hearings have not delivered consistent results. Even MEPs agree that the committees have been crowded, with rambling, poorly co-ordinated and politically partisan questioning.
Alan Donnelly, the leader of Labour's 30 MEPs, argued: "In one hearing there were 70 to 80 MEPs who could have asked a question. There was no structure. In [Philippe] Busquin's hearing, the first question was about his activities as president of the [Belgian] Socialist Party. The next about research policy. Later, they returned to questions on the Socialist Party." He favours smaller teams pursuing a line of inquiry, and would like a treaty change so MEPs could vote down individuals.
The Parliament is an unpredictable place, but as one source said: "Enough of the hearings have gone well for the Parliament to give up the idea of deploying a no vote, and to try to attach conditions to a yes vote." The main political groupings are coalescing around demands for Commissioners to be more available to Parliament, and that if MEPs lose confidence in any individual commissioner action should be taken by Mr Prodi.
Most of these suggestions are vague enough to be acceptable to Mr Prodi, and he is now in a strong position to dictate the detail of any new agreement. The former Italian premier has shown that on some issues he would rather quit than compromise - something which has yet to be digested in national capitals as well as in Brussels.