António Costa took the stance in a post on Twitter, following von der Leyen’s nomination for the post by the European Council and her listing in an open letter some of her main commitments for the next five years.

To be confirmed as president of the European Commission, von der Leyen needs the support of 374 members of the European Parliament - an absolute majority – in a vote that is to take place on Tuesday.

On the eve of the vote, in which Socialist votes may be decisive, Costa publicly welcomed the letter written by von der Leyen – who is currently Germany’s defence minister – namely her "clear commitments" on matters such as "the rule of law, ambition in the transition to neutrality of carbon emissions, promotion of gender equality, solidarity with migrants, development of the social pillar [of the European Union] and a priority for combatting youth unemployment."

The prime minister added: "I also highlight her commitments to deepen EMU (Economic and Monetary Union), using the flexibility of the Stability and Growth Pact, but also the banking union and the creation of a unemployment benefit reinsurance scheme as an instrument for stabilisation in times of crisis."

Costa also expressed the hope that it would be possible to "confirm and clarify" von der Leyen’s vision for the EU during the plenary debate in the European Parliament, on topics such as "cohesion and rural development, the importance of ultra-peripheral regions [such as Portugal’s Azores and Madeira archipelagos] and the need to respond to the housing crisis in Europe."

Von der Leyen is to submit her political guidelines for the next five years to the European Palriament on Tuesday morning, before addressing a plenary session of the assembly. The vote is to take place late afternoon.

If enough Socialists and Liberals vote alongside the conservative European People's Party (PPE), of which Germany’s Christian Democrats form a part, von der Leyen should be approved, despite the fact that Germany’s own Social Democrats have announced their that they will vote against the appointment.

If von der Leyen is not confirmed in the vote, the European Council will have to nominate a different candidate within 30 days.