Voters in Britain and in the Netherlands cast their ballots on Thursday, the start of four days of voting across the EU for the European Parliament.
Portugal’s date for voting is Sunday, 25 May, along with most of the EU’s 28 member countries.
Official results for any nation in the EU will only start to be announced at 23:00 in Brussels on Sunday.
Voters will decide on the composition of the European Parliament’s 751 MEPs.
Seats are allocated in proportion to a country’s population. The UK has 73 seats while the Netherlands with a population of 16.7 million has 26.
Portugal has 22 seats, the same number as Greece, Hungary, and the Czech Republic.
Germany has the largest number (99) while Cyprus, Malta and Estonia have the fewest (6).
The outcome will affect the lives of the EU’s 500 million citizens.
The last elections were held in 2009.