Ursula von der Leyen spent weeks in attempts to convince the deputies of the European Union to support her for a second term as president of the European Commission, reports "Reuters".
A day before the vote, many said they had not yet decided whether to support her.
The European Parliament will decide tomorrow whether to appoint the 65-year-old von der Leyen for another five years at the head of the EC, which would ensure continuity at the top of the 27-member EU at a time of external and internal challenges.
In her first term, Germany's centre-right and former defense minister led the launch of the world's largest policy package to combat climate change, the implementation of Europe's €800 billion response to the COVID-19 pandemic and helped on the mobilization of EU support for Ukraine.
The EU faces an existential threat from Russia's war in Ukraine, uncertainty surrounding the US presidential election in November and an assertive China. Against this backdrop, von der Leyen's supporters argue that she offers stability.
Blocking her appointment after last month's European Parliament elections could throw the EU into a political stalemate amid the growing popularity of far-right and Eurosceptic parties among member states.
It would also create a leadership vacuum, changing the agreement on the rest of the EU's top leadership positions and delaying the start of the new European Commission until 2025.
"We all see the turmoil in the United States. It is extremely clear, we need stability in the European Union", said Bas Eichhout, co-chairman of the Green group in the European Parliament.
Eickhout's 53 Green MEPs and others in the EP insist they will not decide whether to back von der Leyen until she reveals what concessions she is offering in a speech on her plans tomorrow.