Agenda-setting is one of its strongest powers
The European Commission proposes new EU legislation and helps shape the Union's policy agenda. Under the ordinary legislative procedure, a Commission proposal normally goes to the European Parliament and the Council, which must agree on a common text before it becomes law.
That gives the Commission substantial agenda-setting power without making it a European government capable of legislating alone. The distinction is essential: initiating a law and adopting a law are different forms of authority.
The Commission is also an executive and an enforcer
The Commission implements EU decisions, manages funding programmes and the EU budget, negotiates some international agreements and monitors whether EU law is correctly applied. As guardian of the treaties, it can initiate infringement procedures when member states fail to comply with EU law.
This enforcement role can be politically consequential because a rule adopted years earlier may acquire new force through implementation decisions, legal proceedings and funding conditions.
Where the limits sit
Most EU legislation is jointly adopted by Parliament and the Council. Member states also retain vetoes in sensitive areas including much of foreign and security policy, enlargement, parts of taxation and the EU's own resources. Commission power is therefore strongest when treaty authority, legislative support and implementation tools point in the same direction.