(CNN) Europeans rode an emotional roller coaster Sunday. Up, then down.

Hours earlier, European leaders had hailed pro-EU candidate Alexander Van der Bellen's trouncing of nationalist Norbert Hofer in Austria's Presidential election as a victory over nationalism.

French President Francois Hollande tweeted the "Austrian people have chosen Europe."

Germany's Foreign Minister Frank-Walter Steinmeier said "all of Europe is relieved."

Both men are paying particularly close attention as they, along with the Dutch, face their own elections next year.

In a Europe awash with an apparently infectious populism , how votes go beyond their borders is suddenly very relevant.

Their relief over the Austrian vote was short lived. Renzi's referendum defeat hands Italy's EU skeptics a stronger mandate and possibly enough clout in Parliament or the polls to push their agenda.

Could Italy leave the EU?

The biggest winners will be former comedian turned politician Beppe Grillo's Five Star Movement party (M5S) . They are anti-EU and want Italy freed from the constraints of the European single currency. It's the sort of change the EU is unlikely to give easily, if at all.

The stage is slowly being set for a possible Itexit.

Renzi had been doing well in the polls until he staked his political future on the referendum. His enemies saw their chance and pounced, and that includes other anti-EU parties like the Northern League, or Lega Nord.

The message for Brussels is clear; if anti-EU sentiment can bring down the Prime Minister then it might surely pluck Italy from the dwindling group of 27 nations.

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Austrian blow to far right

Austrians, on the other hand, have been swayed over the past six months to move away from Hofer's anti-immigrant, anti-Muslim message.

An annulled election in May put him just 31,000 votes behind Van der Bellen. This time he trailed by 7%.

Hofer said he wanted Austria to remain part of the EU but he wanted changes to Europe's open border policy, not the core ideal of the EU's founding fathers.

But Hofer's appeal might have waned since May in part because of the EU's success in stopping migrants from getting to Austria's borders. The so-called Balkan route was shut down with the help of Turkey and Greece.

So while last year close to one million migrants passed through Austria, helping Hofer's anti-migrant message resonate through Austria's eight million population, it had lost some of its potency come the December vote.

French Nationalist Marine Le Pen responded to Hofer's loss with a tweet congratulating his Freedom Party for fighting "with courage."

"They'll be victorious in the next legislative (elections)!" she added.

Her twitter feed quickly moved on to other topics, an effort it seemed not to dwell on the kick to the nationalist cause.

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Rise of nationalism?

She didn't have to hold her silence for long however, no sooner were the Italian exit polls signaling Renzi's political demise, she tweeted "well done to our friend Matteo Salvinimi for his victory of NO," congratulating the northern Italian nationalist.

She went on to tweet, "The Italians have moved away from Renzi and the EU. We must listen to this thirst for freedom and protection on nations!"

Le Pen's roller coaster went down and then finished high but the ride is far from over.

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Mainstream politicians have been struggling to grapple with her rise -- some point to frustrations over globalization, uncertainty about the economy and erosion of national identity -- even so they haven't found a fix.

And while they take comfort in the victory of pro-EU President elect Alexander Van der Bellen, they will no doubt be pondering what his victory really means.

He isn't just Western Europe's first Green Party President, he is Austria's first President who isn't from the country's two principle political parties.

Sunday's message is clear: European leaders need to brace themselves for a wild ride ahead.