Jean-Claude Juncker, president of the European Commission | Sean Gallup/Getty Images | Sean Gallup/Getty Images Juncker to oppose multispeed Europe European Commission president will also encourage more countries to join euro in set-piece speech.

STRASBOURG — Commission President Jean-Claude Juncker will call for non-eurozone countries to join the EU's common currency in his State of the European Union address in Strasbourg Wednesday, according to an EU diplomat who briefed reporters on the speech beforehand.

Juncker will issue "a strong invitation," the diplomat said, paired with a new "convergence instrument" — money to help countries get up to speed and meet criteria for introducing the euro.

That would mean an incentive for those interested in joining and an offer that will be hard to reject for countries that have said they aren't, such as Poland.

Juncker's speech will also include an outline of proposed reforms of the eurozone's governance, with more detail to be provided later this year. The Commission president wants to bring the European Stability Mechanism "into the EU system," the diplomat said, meaning the European Parliament would have partial oversight over the EU's rescue fund, instead of national governments only.

Rather than creating a new EU finance minister, as proposed by French President Emmanuel Macron, Juncker will call for a European Commission vice president to head Eurogroup finance minsters' meetings.

Opposing plans for the "multispeed" Europe advocated by Macron, among others, Juncker will argue Brexit is an opportunity to come together, as much of the bloc's lack of alignment was caused by opt-outs from common policies and special rules for Britain, the diplomat said. The Schengen travel area and the euro, which every EU country with the exception of Britain and Denmark must officially adopt when they meet the criteria, are two examples of the multispeed EU Juncker will point to.

"This is an opportunity to end that," the diplomat said.

The push for alignment is part of a wider plan to heal Brexit wounds by the time the U.K. leaves the EU.

Juncker will present a "roadmap" for the next 18 months, according to the diplomat, which he will send to national capitals this week. The plan will culminate in a summit on Brexit Day in March 2019.

It will also include a call to make the EU's decision-making more efficient.

Juncker will propose moving from unanimous to majority decisions in areas such as energy, taxation and social policies, where the EU treaty already foresees that possibility (called passerelles in EU-speak). The move would require consent from all EU countries to pass.