Donner says the rise of the populist True Finns party motivated his decision. He believes the True Finns would lead Finland to ruin, as the country is dependent on co-operation with Europe and the European Union.
He also criticised the bigger parties for not clearly differentiating themselves from the True Finns, despite constantly talking about the populists’ rise.
Donner was an MP between 1987-1995, and again for a brief spell in 2007. He left the Social Democratic Party in January.