The expo, to open on 22 May next year, will make the most dramatic transformation to the Portuguese capital since the city was devastated in 1755 by an earthquake and tidal wave. The site, along three miles of derelict waterfront, is Europe's biggest urban project, and any stumble on the race to completion threatens disaster.
Mr Cardoso's walkout was prompted by government anxiety over spiralling costs. Expo authorities promise specific figures later this week, but press reports say that the fair is 7 per cent over budget. Political and personal antagonisms flared between the conservative former European commissioner and the Socialist government. Mr Cardoso, head of Expo '98 since 1992, was confirmed in his post when the Socialists ousted the conservative Social Democrat government in October 1995. They said a change in top management could jeopardise the project's success. But in his resignation letter, reproduced by Lisbon newspapers this week, Mr Cardoso spoke bitterly of having lost the confidence of ministers and facing opposition that amounted to sabotage.
The crunch came in his speech to MPs on 17 January, answering queries from a parliamentary committee set up last year to scrutinise the finances of the fair. Mr Cardoso, defending his record, fatally joked that he deserved a statue in honour of his services.
The minister responsible, Mr Guterres's right-hand man, Antonio Vitorino, replied with a laugh that he had once carried Mr Cardoso as a babe in arms: "I beg him not to turn into a statue because I couldn't bear the weight." No one, he added, was irreplaceable. Crushed by the humiliating riposte, Mr Cardoso quit four days later, along with a phalanx of supporters.
Mr Guterres, in Rome at the time, approached a number of candidates before his close friend, Jose Torres Campos, 64, head of the state roads authority, accepted the job. Announcing Mr Torres Campos's appointment last Thursday, Mr Guterres stressed the need to cut costs.
Some investors privately suspect that the disruption could end up costing even more. But one entrepreneur said yesterday: "I am sure the government will pull out the stops to make Expo '98 open on time whatever the cost, so it does not lose face". He regretted the departure of Mr Cardoso who, he said, had the dynamism "to bulldoze things through".
The 840-acre site is heaving with 5,000 workers and convoys of trucks and excavators giving shape to exhibition halls, apartments and a huge rail and metro interchange designed by the Spanish architect Santiago Calatrava. The first fish for the oceanarium arrived this week,and the new 18km bridge over the Tagus, built by a British-led consortium, is threading across the water.
A spokesman yesterday could not predict the fallout from the upset. He added, however, that polls show massive popular enthusiasm for the venture which was more or less on schedule, "although we have no time to lose".