British Prime Minister Boris Johnson has again rejected a new independence referendum called by Scotland after Brexit.

The head of government told the BBC on Sunday that the referendum does not have “exclusively unified power” and should therefore be held “once in every generation”. In 2014, there was a referendum in Scotland in favor of staying in the United Kingdom.

Scottish Prime Minister Nicola Sturgeon wants to schedule a new independence referendum after the final Brexit is completed at the end of the year. She wants Scotland to be able to rejoin the European Union after leaving Britain. A survey conducted by the Savita Comore Institute in mid-December saw 58 per cent of Scott favoring leaving Britain.

In his experience, referendums are not “particularly joyful events”, Johnson said. The Brexit referendum on the EU’s exit from Britain ended with just 52 per cent of yes votes. The last British vote on membership of the European Economic Community was first held in 1975. Johnson said a generation gap is a “good gap” for the referendum.

Supporters of a new independence referendum in Scotland argue that the 2014 referendum did not expect the outcome of the Brexit referendum. In addition, 62% of Scots voted “no” in Brexit’s referendum.

The decision on a referendum in Scotland rests with Johnson. The pressure may increase if Sturgeon’s Scottish National Party (SNP) wins a major regional election in May.