Interesting about the US senate! I'm not sure that an EU member state can unilaterally make a similar decision though. The treaty is pretty clear that the council is made up by government ministers:

> Citizens are directly represented at Union level in the European Parliament.

> Member States are represented in the European Council by their Heads of State or Government and in the Council by their governments, themselves democratically accountable either to their national Parliaments, or to their citizens.