The entry of new countries into the euro area is determined by the conditions laid down by the Treaty. They are applied in an equal fashion to all candidates.
Powell, Jerome H., “Monetary Policy Influences on Global Financial Conditions and International Capital Flows,” speech at “Challenges for Monetary Policy and the GFSN in an Evolving Global Economy,” Eighth High-Level Conference on the International Monetary System sponsored by the International Monetary Fund and Swiss National Bank, in Zurich on May 8, 2018a.