GEERT WILDERS and his Party for Freedom owe their meteoric rise in Dutch politics over the past years to fierce attacks on Islam. Marine Le Pen’s Front National (FN) built its popularity on campaigns against immigration, back in the days when it was led by her father Jean-Marie. But in recent years both politicians have shifted the focus of their rhetoric towards another bête noire of the far right, the European Union.

On November 13th they held a press conference in The Hague to announce that they will be co-operating in the elections for the European Parliament next spring and hope to form a new Eurosceptic bloc. Their aim, as Mr Wilders put it, is to “fight this monster called Europe”; Ms Le Pen spoke of a system that “has enslaved our various peoples”. They want to end the common currency, remove the authority of Brussels over national budgets, and undo the project of integration driven with so much idealism by two generations of European politicians.

Far-right politicians are a touchy lot, and the new collaboration could be doomed by the same national cleavages that have hobbled earlier efforts to form cross-border Eurosceptic alliances. The European Parliament already boasts one such coalition, the Europe of Freedom and Democracy Group, which has done little to slow integration.

Mr Wilders and Ms Le Pen did not have much to say about how their faction meant to roll back the tide. But it is hard to ignore the fact that these two far-right parties are leading the polls in their respective countries. Given popular anger over Europe’s stagnant economies and a sense of alienation from Brussels, the new alliance between the Party for Freedom and the FN could yet set the tone for next spring’s European Parliament elections.

The link with the FN is the biggest success so far in the quest for international allies that Mr Wilders launched this spring. But building international co-operation between European political parties whose raison d’être is to dismantle European co-operation is no easy task. Britain’s UK Independence Party has rejected the overtures; its leader wants nothing to do with Mr Wilders’s anti-Islam views.

Commentators in the Netherlands expected that Mr Wilders’s courtship of Ms Le Pen would founder similarly. When he launched the Party for Freedom in 2006, he was at pains to insist it would not be a Dutch version of the FN. Mr Wilders is strongly pro-Zionist; the FN is at best even-handed towards Israel, and Ms Le Pen’s father has been charged with denying the Holocaust.

As significant, it is a peculiarity of Dutch politics that gay rights is as much a right-wing cause there as a left-wing one. The Netherlands was the first country to legalise same-sex marriage in 2001, and Mr Wilders often uses accusations of homophobia to bash the country’s Muslim minority. In France the right is culturally traditionalist, and Ms Le Pen opposed gay marriage during the divisive French campaign over legalisation early this year.

But Europhiles hoping that such divisions will doom co-operation are flattering themselves. At their joint appearance, the party leaders easily brushed aside questions about their ideological differences. Mr Wilders said Ms Le Pen was the leader of the FN now, not her father, and that she harboured “not a millimetre of racism or anti-Semitism”. Ms Le Pen said there would be some differences of opinion “even in a marriage” and ridiculed opposition efforts to play up the breach: “In France tomorrow they’ll tell me, oh là l à, Geert Wilders has said this and that about the Koran!”

Perhaps for reasons of political expediency, the FN leader is more careful than Mr Wilders when she explains why Muslim immigration is a grave threat. He calls for a ban on the Koran and claims that Islam is a fascist ideology. Yet their views are not that far apart: Ms Le Pen is facing charges for comparing the spillover of Islamic prayers into the streets to the Nazi occupation and she recently sparked a furore when she seemed to suggest that four French hostages released by al-Qaeda after years in captivity had become Islamists because they sported long beards.

Political analysts see little reason why the two parties’ far-right voters would be alienated by associations with foreign parties. Mr Wilders’s voters tend to be at the lower end of the informational spectrum and, while they resent Brussels, they have little interest in the internal politics of other European countries. Among the Party for Freedom’s voters, says Chris Aalberts, a Dutch expert on the party, “nobody knows what Marine Le Pen thinks or what her standpoints are”.

The larger question may be what, given the disconnect between national political environments in Europe, the two party leaders expect to gain from their alliance. Ms Le Pen’s answer was the most interesting: “The time when patriotic movements were divided, intimidated, or even terrorised by demonising each other—that time is over.” For far-right nationalist parties, international co-operation accords a type of recognition that could help overcome the disdain and antagonism of the press and political elites. The Party for Freedom and the FN are already riding high in the polls among voters who want to send a message of protest. If international co-operation leads voters to take them more seriously, European elections next May could end up sending a strong one.