EU leaders are today expected to appoint the Spanish Secretary-General of NATO, Mr Javier Solana, as the European Union's first foreign and security policy chief, known as "Mr CFSP", in a move that will emphasise the growing extent to which the two organisations are marching in step.
Despite the embarrassing symbolism and timing for Ireland, just days before the European elections, the Taoiseach, Mr Ahern, is likely to back Mr Solana for the job, which Ireland had once canvassed for the former Tanaiste, Mr Dick Spring.
Indeed, the two-day summit in Cologne is likely to be dominated by defence concerns, with Finnish President Martti Ahtisaari also due to report today on his talks in Belgrade, and the German EU presidency seeking an ambitious commitment on enhancing the Union's own military capabilities.
Leaders will also hear tonight from the Commission president-designate, Mr Romano Prodi, about his plans for reform of the Commission although, sources close to him say, he will insist that any discussion of names is premature and will reject any attempt by the large countries to claim particular portfolios.
A key element of his speech is likely to be an attempt to respond to parliamentary demands for extra powers over individual commissioners, by insisting on the need to preserve the institutional balance in the EU. It is an insistence that is likely to be reassuring to small countries, which view the growing power of the Parliament with mixed feelings. Mr Prodi is also expected to say that he has made good progress in defining portfolios and that there will be no problem in each of the 19 other members being given a substantial responsibility. Some will be given new co-ordinating roles and a special emphasis will be placed on the "core policy" of reform of the Commission.
And he is likely to stress the need to internationalise the cabinets of individual commissioners.
That process of internal reform will be complemented by a summit decision to launch a treaty-amending mini-intergovernmental conference in May next year, to be completed by December, on the so-called unfinished business of the Amsterdam Treaty.
This consists largely of the re-weighting of votes in the Council of Ministers in favour of the larger countries in exchange for the loss of their second commissioner. But many member-states also want to expand the remit of the debate to the issue of further curbs on member-state vetoes and more qualified majority votes (QMV).
Ireland is keen that the conference remit should be very limited - largely to avoid the necessity of a further referendum - but is likely to have to accept some discussion on QMV as only Spain is currently strongly opposed.
Other jobs will also be up for grabs over dinner tonight. A deputy head of the Council of Ministers secretariat is likely to be appointed, with three diplomats strongly in the running, Britain's Sir David Hannay, and the French and Danish ambassadors to the EU, the colourful and outspoken Mr Philippe de Boissieu and Mr Poul Chrisstopherson. Ireland is likely to favour the latter. And the presidency of the European Investment Bank is likely to go to another Spaniard, the former minister Mr Pedro Solbes.