The European Parliament is to vote on Jean-Claude Juncker's nomination to replace Jose Manuel Barroso as head of the European Commission.
Juncker needs an absolute majority of 376 votes in the 751 seat Parliament to get the job.
The vote has been brought forward by a day to allow enough time before EU leaders meet in Brussels to decide on a package of other top EU jobs.
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The Islamic centre where the Manchester suicide bomber is thought to have prayed says the attack "has no place in Islam or any religion".
German chancellor Angela Merkel and Indian prime minister Narendra Modi among those to praise "great spirit" of Manchester people.
The bomber's identity has been confirmed by Greater Manchester Police.