I have outlined the current rules, which can be summed up as the European Council proposes and the European Parliament approves (or doesn't approve!) of the choice.
One feature of this system is that some Europarties are proposing candidates for the post of President of the European Commission - the Party of European Socialists is proposing Martin Schulz, of the German Social Democrats, who is currently the President of the European Parliament; and the Alliance of Liberals & Democrats for Europe is proposing Belgium's Guy Verhofstadt, of the Flemish Liberal Democrats, currently leader of the ALDE Members of the European Parliament.
The European People's Party is soon to chose their proposed candidate - likely to be Luxembourg's former Prime Minister, Jean-Claude Juncker, of the Christian Social People's Party.
Recently, Daniel Hannan, a Conservative MEP for South East England, confirmed that the Alliance of European Conservatives & Reformists would not be proposing a presidential candidate.
Unremarked, the EU is about to hold its first federal elections. The European Parliament has been quietly sucking in more power for decades, but has so far lacked the supreme attribute of a federal legislature, namely the right to appoint a federal government.
I have to disagree with him here, as the "supreme attribute" of a federal legislature is not appointing a "federal government".
The most obvious example of a federal nation with an executive President (a point I will need to come back to) is, of course, the USA. And I am sure it would come to a surprise to Senators and Congresspersons that the "supreme attribute" of their federal structure is appointing the federal government. In normal circumstances, they have the same right that every American has - namely to vote for members of the Electoral College. It doesn't matter whether you're the Speaker of the House of Representatives or the Senate's President pro tempore - you have the same number of votes as anyone else, i.e. one.
Only if the Electoral College fails to elect a President and/or a Vice-President does Congress get involved in breaking the deadlock.
In British discussion of the European Union, it always seems that "federal" and "federalism" mean the exact opposite of what they actually mean - federal and centralised are very different. How can you have a centralised federal state?
One crucial thing about American Presidential elections is that they are not necessarily won by whoever gets the highest number of popular votes - what counts is Electoral College votes. And 48 of the States (all apart from Maine and Nebraska) and the District of Columbia work on a "winner-takes-all" system, so effectively it's about winning whole States.
There is another way of distinguishing between political systems - there is the presidential-congressional system and the parliamentary one. In the former, the executive has a mandate which is distinct from the legislature's, whilst in the latter the executive draws its legitimacy from the legislature.
The European Parliament is misnamed, as it is much closer to a Congress. And my worry is that if Schulz becomes Commission President, then this congressional aspect will be damaged.
The EU's federalism is drawn from Germany's. For example, Germany has its Bundesrat, where the Länder are represented - or to be more precise, their executives are represented. Each Land has between 3 and 6 votes. Note that this does not mean that a Land with 3 votes can cast 2 for and 1 against - it could either cast 3 for or 3 against (or else abstain). And, in the same way, in the Council of Ministers and the European Council each nation has between 3 (Malta) and 29 votes (for the UK, France, Germany and Italy).
There is another way that the EU follows Germanic federalism. The German President nominates a Chancellor, and the Bundestag can elect that candidate by an overall majority.
And the European Council nominates a Commission President, whom the Parliament can elect only by an overall majority.
It is important to note that the Parliament is going beyond the Treaty of Lisbon, as the Council is only required to take account of the Parliament election results when nominating a candidate for Commission President. Nothing about Europarties nominating Presidential candidates - although in the German system, parties do nominate Chancellor candidates, who need not be the party leader.
There is one objection from the Centre for European Reform, in a pamphlet The 2014 European elections: Why a partisan Commission president would be bad for the EU, which makes a powerful case that can be summed up with the idea that the President should be an umpire, not a captain of one of the teams:
Commission presidents are usually politicians with a background in one party or another, but they have never before had a mandate to achieve one party’s programme. They can only perform their function properly if they respect the Commission’s role as the impartial "guardian of the treaties" that pursues the broad European interest. This role of the Commission is vital to the EU’s system of rule of law. When taking office, every commissioner takes an oath to be "completely independent in carrying out her responsibilities, in the general interest of the Union.” This pledge loses its meaning if the president of the College is explicitly partisan
So, how partisan would a President be? The European Council nominates by Qualified Majority Voting - the total votes in the Council are 352, and for something to pass under QMV, it needs to have 260 votes. It also needs the support of 15 nations (while it isn't possible for 13 nations to produce 260 votes between them, there are combinations of 14 nations that can pass the 260 mark).
If we look at the number of votes in the Council, the EPP has 151, PES 118, AECR 29 (the United Kingdom's) and ALDE 21. That makes 319, so there are 33 votes not accounted for. Italy's 29 are cast by its new Prime Minister, Matteo Renzi, of the Democrats. Although his party's MEPs sit in the Progressive Alliance of Socialists & Democrats grouping, his party is not part of any Europarty. Slovenia's 4 votes are cast by its Prime Minister, Alenka Bratušek, of the Positive Slovenia party - but her party is applying to join the ALDE.
If 260 votes are needed, then it is obvious that it takes 93 votes to block. And so either the EPP or PES could block in the Council. Hence the "winner" of the Parliamentary election could have nominated a candidate who is unacceptable to the other main party. Any potential Commission President has to be a consensus builder.
And if each Head of Government appoints a Commissioner from their party, then the EPP and PES would have 11 Commissioners each, with the ALDE 3 and AECR 1 (and 2 others). Hence, a balanced Commission politically.
If we look at the American system, then the incumbent President, Barack Obama, is the first person since John Kennedy to be a member of the legislative upon election. All intervening Presidents were either Vice-President (and hence involved in the work of the federal government) or a Governor (and hence running a state government). Yes, there were former Congressmen becoming President - both Gerald Ford and the elder George Bush were ex-Congressmen when they became President, but the trend was to either be involved in the legislature or following the path of government.
And when it comes to Commission Presidents, we see something similar among the 11 men who have held the post. Since Luxembourg's Gaston Thorn took office in January 1981, every President - apart from France's Jacques Delors - has been a Prime Minister. Every President apart from the Netherlands' Sicco Mansholt (who was the Commissioner for Agriculture when chosen as President) has been a Prime Minister or a Finance Minister.
An incoming President is someone who is either a sitting Commissioner or has held a very senior office in their national Government.
And hence one reason why I am concerned if Schulz ends up as Commission President. In a parliamentary system, a party "wins" and then goes on to provide the Prime Minister. Schulz's becoming President would tip the Parliament to being a Parliament rather than a Congress and alter its relationship with the Council. A pattern would be established where someone builds up a career as an MEP, ends up leading a group, and when that group "wins" becomes Commission President. What would count would be being a consummate Parliamentary insider rather than having built up a career in a national government making executive decisions.
At one level, this would change what the EU is. Just as the way the American President is elected hammers home that fact that the USA is a collection of states, the way the Commission President is chosen emphasises that the EU is a collection of nations, with it being national leaders being the first stage of deciding who the President is.
Hannan is wrong to see this as a federal election or about a United States of Europe. This is the main Europarties trying to bounce the national leaders into selecting a certain person - whether it be Schulz, Verhofstadt or Juncker - and hence making the input of national leaders to the process irrelevant. It is trying to reduce the European Council (which represents the nations) to be a rubber-stamping body, with the decision as to who is
Prime Minister of Europe Commission President being made by whoever "wins" the Parliament election. Just as the federal USA ensures that States - as individual States - play the key role in the election of the President, a federal USE would ensure that nations - as individual nations - play the key role in the election of the Commission President. This is bypassing the nations, something completely different....