From the Netherlands and France to Denmark and Austria, eurosceptic voices have been growing for some time, and would take succour from a 'Leave' vote by British voters on Thursday.
The European Union's nightmare scenario is that Brexit would trigger a domino effect and could ultimately lead to the dissolution of the 28-nation bloc.
A recent study by the Pew Research Centre found that over 40 percent of Europeans say they want more power returned to their countries.
Dutch far-right MP Geert Wilders, whose anti-Muslim party is topping polls ahead of elections next year, is a leading light in the EU's small but vocal “out” brigade.
The firebrand politician has promised to pull the Netherlands immediately out of the “totalitarian” EU in case of electoral victory.
In France, Marine Le Pen of the far-right National Front has been less direct in her rhetoric, but nevertheless vowed to hold a referendum on the country's EU membership if she becomes president in 2017.
Calling herself “Madame Frexit”, she said Brexit would prove that “it is possible to live outside the EU”.
“France has possibly a thousand more reasons to want to leave the EU than the English,” Le Pen said at a gathering of far-right parties in Vienna on Friday.
In Italy, another hotbed of populist resurgence, the Northern League also wants to quit the EU.
“If this is Europe, it's better to be alone than in bad company,” its leader Matteo Salvini said recently.
While some simply want out, a majority of populist groups remain less radical in their approach.
Instead of leaving, parties like the Alternative for Germany and Austria's far-right Freedom Party (FPOe) want to regain more sovereignty.
“We love Europe (but) it needs improvement,” insisted FPOe leader Heinz-Christian Strache who has his sights set on becoming chancellor in 2018.
Experts note that Nordic countries, where populist parties are now either in government or represent a strong opposition force, are particularly prone to calling a referendum to renegotiate their EU membership.
“Small countries that are economically at least as affluent as the UK are the main ones at risk, especially Denmark and potentially also Sweden,” said Carsten Nickels of the Teneo analyst group in Brussels.
Many Scandinavians fear that the crises battering the bloc will affect the social fabric and standards of their respective welfare states.
Loud bark, no bite
Among the bloc's loudest critics are right-wing populist governments in Hungary and Poland, which regularly launch blistering attacks on the EU.
However, as newer member states, they are also among the biggest recipients of EU aid.
Much of the tough talk is in fact aimed at voters at home, experts say.
“Poland and Hungary without the European Union would not have any chance economically or politically and they know it,” said Werner Fasslabend of the Austrian Institute for European and Security Policy in Vienna.
Neither country is in favour of Brexit, with Hungarian Prime Minister Viktor Orban urging Britons to vote to remain in the EU in an open letter published in British media on Monday.
“Hungary is proud to stand with you as a member of the European Union,” the ad read.
Even Hungary's radical right Jobbik party recently dropped its push to leave the EU, saying the migration crisis offered a chance to “transform” the bloc from within.
While Brexit may fuel eurosceptic dreams of power, the populist lobby remains a fragmented bunch pushing very different agendas.
In wealthy northern and western European countries — the destination of hundreds of thousands of refugees last year — right-wingers have taken centre stage, railing against migrants and bailouts.
Down south, on the other hand, the financial crisis has sparked radical left movements like Spain's anti-austerity party Podemos, tipped to come second in elections three days after the UK referendum.
Beyond this division, there is also a gap between pre-election rhetoric and the reality of being in power, said Finnish political expert Emilia Palonen.
She pointed to the leader of Finland's nationalist Finns Party who dropped his “virulent calls for an EU exit” after becoming foreign minister last year.
And the winner is…
Experts say Russian President Vladimir Putin will rub his hands in glee at the prospect of a weakened Europe if Britain opts out.
“If the EU loses its power and is very much occupied with its own problems… Putin will use this chance to regain (former Soviet countries),” said Fasslabend.
The vote would also provide fodder for domestic propaganda, said Russian expert Sergei Utkin.
“Brexit would be another piece of (Russia's) ideological claim that Europe is falling down,” he told British newspaper the Guardian.