The EU Commission has strong powers because it has the monopoly on proposing (initiating) laws in the EU. However, the Commission is not an elected body.
The Future
The EU Constitution proposes to allow a qualified majority in the European Council to elect the Commission.
Federalists therefore propose that the Commission President and his colleagues should be elected by the EU Parliament and be responsible to the Parliament.
Euro-realists and eurosceptics propose that every national parliament elects its own national Commissioner, who could also be sacked by the respective national Parliament.
The President of the Commission should then be elected by the national Parliaments in unison.