As part of the task that faces him, he was in London yesterday for meetings with John Major, Kenneth Clarke and the Labour leader, Tony Blair. It falls to Mr Santer to allocate portfolios among the 21 members of the new Commission, which begins a five-year term on the 1 January 1995. The job could soon become a nightmare: Mr Santer must try and allocate jobs and responsibilities among some of the most formidable players in European politics - without upsetting their sponsors in the 16 governments.
Britain's senior Commissioner, Sir Leon Brittan, who holds the important foreign trade portfolio - making him the second most powerful figure in the Commission after the president - is busy fending off challenges from a number of quarters and may see his stature diminish. The biggest threat is coming from the senior incoming French Commissioner, Yves-Thibault de Silguy.
'Somehow Santer has to fashion from the raw material a Commission that can run a coherent policy for the next five years, that can guarantee both continuity and innovation,' said one diplomat yesterday.
Mr Santer's task of squaring candidates with jobs is complicated by the addition of at least one new EU member state (Austria) and probably three others - Sweden, Finland and Norway, depanding on the outcome of referendums - in January. It has already been agreed they will each appoint an EU Commissioner. Mr Santer's task is to to distribute the existing 16 posts and create four new ones, while retaining some responsibilities for himself.
Just as in national governments, the foreign affairs portfolio, currently shared between Sir Leon and the Dutchman Hans van den Broek, is the most coveted in the Commission. Sir Leon has frequently strayed into other Commissioners' areas of responsibilities and he has sparred with Mr van den Broek, whose portfolio covers defence and enlargement. The division has never been happy for Mr van den Broek. There is no common EU defence policy to speak of, and the enlargement process towards Eastern Europe involves negotiating what are essentially trade agreements and thus has fallen to Sir Leon.
France is seeking important portfolios for Mr de Silguy, the European adviser to the French Prime Minister, Edouard Balladur, and Edith Cresson, a former Socialist prime minister. And Italy, after years of sending relative lightweights to Brussels, is now trying to improve its standing by securing important posts for its candidates.
Belgium's Karel van Miert, who holds the competition portfolio, hopes to keep it and the senior German Commissioner, Martin Bangemann, also expects to hold on to the industry portfolio. There is some speculation that he may take on responsibility for the development of high-tech industries and the coming information superhighway, already a particular interest of his.
Mr Santer's appointment does free up the important agricultural job now held by Luxembourg's Rene Steichen, and it will be hotly contested since it is one of the big spending departments. A Southern European is favoured because the south is likely to suffer most from any further reform of the Common Agricultural Policy.
'It is like a 3-D puzzle; everything you have already put in place falls apart with the next move,' said a Commission insider. Everyone is hoping the pieces will fall neatly in place by December.