India, April 15 -- "Today, we celebrate. Tomorrow, we work," Peter Magyar, 45, Hungary's new Prime Minister (PM) shouted out to massive crowds late on Sunday night. He had just been voted in with a thumping two-thirds majority, inflicting a humiliating defeat on Viktor Orban, Europe's longest-serving leader.

As the vote count piled up, so did the hordes of mainly young people choking the banks of the Danube around Budapest's parliament building, a somewhat modest replica of Westminster. The chain bridge linking downtown Pest with the elegant hills of Buda reverberated with light and sound marking the victory of a young and as-yet-untried new party, the Tisza. Its leader, a personable 45-year-old apparatchik, who broke ranks with his form...