A sovereign has a monetary and fiscal authority which is solvent by legal fiat in its own currency. By that definition no Eurozone state is sovereign, and in fact the ECB ranks above them all because the ECB can actually tighten the monetary thumbscrews on states in order to enforce policy changes outside the ECB's statutory purview.

Therefore, what you claim there is a popular majority implies rolling back to before the Maastricht Treaty.

If you are not convinced, try it on someone who has not been entirely debauched by economics. — Piero Sraffa