David Cameron said the nomination of Jean-Claude Juncker as European Commission president represented "a bad day for Europe".
"This whole process has reinforced my view that Europe needs to change. If you are deadly serious that you want change, as I am, then you don't back down when a vote goes against you," the Prime Minister said.
"This is a bad day for Europe. It risks undermining the position of national governments and hands new power to the European Parliament."