On 1 May, the ten accession states join, boosting the ranks of the community to 25 and swelling the population of this single market to 470 million consumers.
Hot on the heels of enlargement come elections in June, with estimates that almost two thirds of the 727 MEPs will be newcomers to the European Parliament.
Finally, set for November is the formation of a new commission under a new president, with horse-trading for key positions sure to keep the Brussels rumour mill crackling for the next six months.
Add to this heady mix the ongoing discussions on a European constitution and a change in the voting structure of the European Council in response to enlargement. Each accession country has nominated its own commissioner to join the college - the collective term for the EC commissioners. For the first six months, these ten (see panel) will 'shadow' an incumbent commissioner, to help them develop an understanding of EU culture and procedures. And then, from November a full complement of elected commissioners from each member country will take their places for a five-year term. So what does EU enlargement imply for Euro lobbyists with so many new faces and priorities to get to know?
'While the college is still discussing how they will share the work, the new candidate commissioners will have to devote significant time to the hearings planned with the European Parliament,' says Hill & Knowlton chairman of global PA Elaine Cruikshanks.
Certainly, they will be working towards the implementation of the new EU constitutional treaty, and can be expected to play a very strong role of communicating with home countries to promote better understanding of the EU.
At the same time, the new commissioners have to settle in and form their cabinets, although these cannot be finalised until portfolios have been agreed.
Uncertainty in this area is leading some lobbyists to hold back until the smoke clears. 'The question is, do you invest a lot of energy or resources to relationship management when it is not clear whether they (the commissioners) will stay in their current position,' says Red Cross EU Office director Luc Henskens.
One advantage of the six-month shadowing period may be to give the new commissioners time to meet with lobbyists. Indeed, they may even welcome such meetings as a means of getting up to speed on particular industries or business issues. Cruikshanks concedes that the direct lobbying impact may be limited, but will at least enable industry to start a relationship with people who are likely, in some capacity, to be on the scene for the next five years.
Patterns of decision-making within the EU are expected to change owing to the infusion of new blood.
'Each new commissioner will bring a different perspective to EU policy-making,' says APCO director Europe, strategic communications, Cleopatra van de Winkel. 'In general, the new group is politically centrist to centre-right, with many of the candidates from the former Eastern Bloc being strong reformist, free-market supporters.'
Indeed, a number of the candidates have already called for budgetary reform, particularly in the area of agricultural spending. A couple want a more flexible Growth and Stability Pact.
Ray Georgeson, director of policy at recycling organisation WRAP, hopes that EU membership will lead many accession countries to 'raise their game' to comply with EC directives. But there is also a danger they could derail some important EU moves on recycling.
'It's possible they may want Europe to look afresh at landfill and packaging recycling targets that will create a lot of uncertainty,' says Georgeson.
From the perspective of smaller accession states joining the EU, the fear is whether their voices will be overwhelmed by the administrative culture of the EU. This is likely to present some public affairs opportunities.
'Consultants and their clients can help them integrate into the EU because we are familiar with the legal and regulatory environment and will be able to speed up their learning curve,' says Citigate Public Affairs EU office executive director Thierry Lebeaux.
Although all is still to play for, it is thought unlikely that plum portfolios, such as the internal market, competition and agriculture will be awarded to commissioners from the new member states this time. But it will be interesting to see what influence new commissioners are able to exert on structural and regional funds.
'Lobbying opportunities may increase from the fact that portfolios will be split to accommodate all commissioners, which will open avenues that did not exist when only one commissioner was dealing with them,' explains Lebeaux.
Enlargement has also changed the voting structure of the Council. The current 'big five' - France, Germany, UK, Spain and Italy - will continue to dominate. However, Poland, due to its 40 million population, will be allocated the same number of votes as Spain.
'We should not ignore the relatively strong representation of smaller member states, especially when they form alliances,' says Cruikshanks.
'When it comes to getting messages across to the new institutions, coalition building is going to be important, as will the ability to network more broadly across member states and industry alliances.'
Over the next 12 months it will become apparent who the big hitters are, and smart public affairs strategists will move swiftly to identify where influence lies. Enlargement offers big opportunities.
Commissioner shadowing: Michaele Schreyer (Budget). Cyprus's minister of
finance studied law at Cambridge and Harvard.
He has been involved in the Council of Europe and the Organisation for
Security and Co-operation in Europe.
Commissioner shadowing: David Byrne (Health and Consumer Protection).
Telicka forged his career in the Czech Foreign Affairs department after
graduating with a law degree from Charles University, Prague, in 1986.
Commissioner shadowing: Viviane Reding (Education and Culture). Finance
minister since 2001, she is known for her fiscal frugality, free market
and pro-Western stance, and has been vocal on the need for budgetary
reform, especially CAP.
Commissioner shadowing: Michel Barnier (Regional Policy and
Institutional Reform). A 62-year-old economics graduate, Balazs has been
Hungary's ambassador to Denmark and Germany. He edits Europa Forum, a
quarterly review of European integration.
Commissioner shadowing: Franz Fischler (Agriculture, Fisheries and Rural
Development). As well as being a founder of the Latvian People's Front,
foreign minister Kalniete has been Latvian ambassador to the UN, France
and to UNESCO.
Siim Kallas Estonia
Commissioner shadowing: Pedro Solbes (Economic and Monetary Affairs).
Estonian prime minister between January 2002 and April 2003, Kallas's
government career has spanned foreign affairs and finance briefs.
Interested in economic and monetary affairs.
Commissioner shadowing: Poul Nielsen (Development and Humanitarian Aid).
Malta's foreign affairs minister for five years. Has lectured on
company, industrial and European law. A former director of the Central
Bank of Malta, he follows human rights issues.
Commissioner shadowing: Pascal Lamy (Trade). Poland's minister for
European affairs has studied in the US, UK and Spain. Hubner's career
includes a stint in economics journalism and acting as Poland's chief
negotiator for OECD membership.
Jan Figel Slovakia
Commissioner shadowing: Erkki Liikanen (Enterprise and the Information
Society). Extensive parliamentary experience; participated in Council of
Europe committee on Agriculture and Rural Development and International
Commissioner shadowing: Gunter Verheugen (Enlargement). European affairs
minister. Head of the team negotiating Slovenian accession since 1998.
Spent eight years as director of the Institute of Microeconomic Analysis