by a qualified majority. This is the 27 heads of government/state (eg 'of government' in our case - the PM; 'of state' for France - their president).
In theory, this President of the European Council doesn't have 'power', he/she just leads the meetings of the council:
6. The President of the European Council:
(a) shall chair it and drive forward its work;
(b) shall ensure the preparation and continuity of the work of the European Council in
cooperation with the President of the Commission, and on the basis of the work of the
General Affairs Council;
(c) shall endeavour to facilitate cohesion and consensus within the European Council;
(d) shall present a report to the European Parliament after each of the meetings of the
European Council.
The President of the European Council shall, at his level and in that capacity, ensure the
external representation of the Union on issues concerning its common foreign and security
policy, without prejudice to the powers of the High Representative of the Union for Foreign
Affairs and Security Policy.
The President of the European Council shall not hold a national office.’.
http://europa.eu/lisbon_treaty/full_text/index_en.htm (Article 1)
so that's why it's not a democratically elected post. But the post's influence will be a lot, I think. I really,
really want someone other than Blair to get it.