From her nondescript offices in the Paris suburbs, ­Marine Le Pen — the blond, hazel-eyed face of France’s far right — is leading the charge to build a new alliance of European nationalists, this time by blitzing the ballot box.

A 45-year-old lawyer who wants to halt immigration, Le Pen led France’s National Front to historic gains in local elections last month. She did it by destigmatizing the party co-founded by Jean-Marie Le Pen, her 85-year-old father, who once called the Nazi gas chambers a mere ­“detail” of history and lost five bids for the French presidency.

In appearances across the country, the younger Le Pen is rolling out a more tempered brand of nationalism that has become a new model across Europe, rejecting her father’s overt racism and playing down the party’s former links to Nazi collaborators. All the while, she is tapping into the rising economic despair of a nation as well as a backlash against the European Union, the 28-country bloc headquartered in Brussels.

(Read: Q&A with Marine Le Pen)

Now she is training her sights on a larger prize. From Sweden to Austria, Britain to Italy, nationalist and far-right parties are poised to make record gains next month in elections for the European Parliament. Rather than see their power diluted, Le Pen is seeking to unite a variety of such parties into an extraordinary coalition of anti-E.U. nationalists.

Together, she said, they would work to turn back the clock on the integration and open borders that have defined post-World War II Europe. “You judge a tree by its fruit,” she said last week in her office, a statuette of the Greek goddess of justice resting on a shelf above her. “And the fruits of the E.U. are rotten.”

But these are, after all, nationalists, and forging an international alliance of xenophobes is proving to be just as hard as it sounds. On a continent riddled with old grudges and the ghosts of battles past, working together — for some, anyway — means setting aside centuries-old animosities.

Hungary’s far-right Jobbik party, for instance, remains locked in a war of words with its counterparts in Romania and Slovakia over Hungarian-speaking regions in those countries that date to the breakup of the Austro-Hungarian Empire. Far-right Italians, meanwhile, are at odds with Austria’s Freedom Party over the fate of Alto Adige, a largely German-speaking enclave in northern Italy that has been the site of a political tug of war for years.

But there is also a lingering question about just how much certain parties have truly changed. Indeed, even as Le Pen and her European partners seek to shed their image as far-right extremists, their words have often seemed to undermine that effort.

Le Pen’s closest ally, Geert Wilders in the Netherlands, sparked outrage at home last month after fiercely promising his faithful that he would work toward having “fewer Moroccans” in the country. Last week, the Austrian Freedom Party’s Andreas Mölzer pulled out of his campaign for reelection to the European Parliament after calling the diverse bloc “a conglomerate of Negroes” whose regulations were worse than Germany’s Third Reich.

But unlike her father, who was accused of being anti-Semitic, Le Pen has been accused of espousing Islamophobia — a word she dismissed in an interview as “a creation of the Islamic Republic of Iran.”

Yet she has appeared to push the envelope recently, telling French radio that pork-free meals for Muslim and Jewish children would be banned in the cities and towns now controlled by her party. In an interview with The Washington Post, however, she seemed to backtrack, saying that both pork and non-pork meals would be offered in schools.

And although they agree on the fundamental issue of loosening the ties that bind the E.U., the parties remain deeply at odds over a host of issues, including same-sex marriage. The track record for cooperation among members of the far right also bodes ill. Such parties have repeatedly sought to build alliances in the European Parliament, only to see them fall apart because of infighting.

“Nationalists inherently disagree with each other,” said Simon Hix, a professor of comparative politics at the London School of Economics. “They’re all like, “My country is the best one in the world,’ and then the other one says, ‘No, my country is the best one in the world.’ And from there, they all end up fighting.”

But Le Pen insists that this time will be different, that she is gunning for a big win next month. A strong showing by the nationalists, which opinion polls in multiple countries suggest could happen, could effectively put some of the E.U.’s toughest opponents inside its gates.

Once viewed as a paper tiger, the European Parliament, based in Strasbourg, France, has continued to gain power. Even in the best-case scenario for Le Pen, any far-right alliance is unlikely to unseat Europe’s mainstream majorities on the center-right and center-left.

But the vote — over four days starting May 22 — could make the far right a stronger force on issues such as immigration legislation and rights of religious minorities. In the name of protecting domestic industries, far-right representatives would seek to bring free trade to a standstill — for example, opposing any attempt to ratify the sweeping E.U.-U.S. free-trade deal that is under negotiation. Analysts say a stronger far right could compel mainstream conservative parties to tow a harder right-wing line.

With France’s National Front the likely anchor of any nationalist coalition, it has been up to Le Pen to try to forge a legislative bloc. Success would mean winning at least 25 seats from seven countries. Though almost assured of enough seats, Le Pen appears to be at least one nation shy of the country threshold.

That is partly because of the varying degrees of extremism tolerated by each party. Le Pen dismissed the notion of working with the black-clad ultranationalist members of Greece’s Golden Dawn, whom she described as “neo-Nazis.” She also ruled out collaborating with Hungary’s Jobbik party, one of whose leaders has called for a government list of Jews in the name of national security.

Meanwhile, one nationalist group, the United Kingdom Independence Party, has refused to work with her. Like Le Pen, UKIP chief Nigel Farage has sought to position his party as sane moderates who happen to have an anti-E.U., anti-immigration bent. While he touts his party as mainstream, Le Pen’s National Front, he insists, is just faking it.

“Our view is that whatever Marine Le Pen is trying to do with the Front National, anti-Semitism is still imbedded in that party, and we’re not going to work with them now or at any point in the future,” Farage told Britain’s Telegraph newspaper.

But even her critics concede that Le Pen has determinedly sought to distance herself from her controversial father and has made strides toward steering the party away from explicit racism. In October, the National Front ejected a mayoral candidate, Anne-Sophie Leclere, after she publicly compared France’s French Guiana-born justice minister, Christiane Taubira, to a monkey.

In fact, Le Pen is portraying the party as the best ally French Jews could have against a common enemy.

“Not only am I not anti-Semitic, but I have explained to my Jewish compatriots that the movement most able to protect them is the Front National,” she said. “For the greatest danger today is the rise of an anti-Semitism in the suburbs, stemming from Muslim fundamentalists.”