When Europe Goes to the polls on 23 May, the right-wing campaign spearheaded by Italy’s Matteo Salvini – leader of The League – could change the shape of European politics. Subscribe to our channel here: https://goo.gl/31Q53F Salvini is trying to create a nationalist bloc that would be the second biggest force in the European parliament. But where would that leave the centre-left or social democrats, who for decades were a natural party of government across Europe? Three former leaders – Tony Blair, Matteo Renzi and Helle Thorning-Schmidt – offer their thoughts. BBC’s Diplomatic Editor Mark Urban reports.