France’s far-right this weekend selected a party leader from outside the Le Pen dynasty for the first time in its 50-year history — the latest sign of the movement’s bid to convince voters it has swapped extremism for professionalism.

Before a cheering auditorium, Marine Le Pen announced on Saturday evening that her protégé Jordan Bardella, a 27-year-old member of the European parliament, had won the vote to succeed her at the helm of the Rassemblement National (National Rally). “I will pass on a re-founded and revitalised party . . . that is proving every day that it is a real party of government, the party that will govern tomorrow,” the 54-year-old said. “We must be ready!”

The succession will not alter the power dynamics — Le Pen remains the RN’s uncontested boss. Bardella, in a relationship with her niece, is almost family. Nor is Le Pen’s long-held strategy of detoxifying the RN’s image and courting new voters by focusing on the cost of living crisis gripping Europe expected to change.

But the shift comes at a difficult moment. Old demons resurfaced last week when Grégoire de Fournas, a RN lawmaker, was sanctioned for shouting “Go back to Africa” as a black MP was speaking about dangers migrants faced in parliament.

The incident is the party’s first mis-step since its unexpected win in June legislative elections that made it the biggest opposition party just as President Emmanuel Macron’s centrist alliance lost its majority. It now has 89 MPs, its biggest haul, and up from just seven in 2017.

The win, which came less than two months after Le Pen lost her third presidential bid and hinted she could retire, transformed the party’s fortunes and rekindled hopes they could win in the next presidential election in 2027.

Although the RN cannot pass laws alone, it is for the first time playing a role in day-to-day lawmaking, occupying prestigious posts in the National Assembly, and training up a group of experienced national leaders.

Jean-Yves Camus, a political scientist who specialises in European nationalist movements, said the elevation of Bardella was another sign of how the RN was seeking to move on from the era of founder Jean-Marie Le Pen, who was convicted of racist speech and Holocaust denial.

“There is a new generation of politicians in the RN who came of age under Marine and not her father,” he said. “The election of the 89 MPs is an earthquake, but it’s a victory that brings new obligations. They must show that their MPs are mainstream and respectable, they do the work, and that they do not go off the rails.”

Things got off to a good start in the National Assembly. Le Pen positioned the RN as the responsible, suit and tie-clad opposition that was fighting for French people, in contrast with the leftwing Nupes alliance, who she slammed as rowdy and unpatriotic.

RN votes helped the Macron government pass a key law to protect households and companies from rising energy costs. But then it wrongfooted everyone by changing position to vote for a no-confidence motion in Macron’s government sponsored by the left. The motion failed, but Le Pen’s pivot put the government on notice that the RN might one day help bring it down.

Most importantly for the chronically indebted RN, the 89 MPs represent an annual cash infusion of about €10mn — double the amount in the last parliamentary session. Under France’s public financing system, parties get payments for each elected official and their overall vote tally. Party officials said they would use the funds to gradually pay back a contentious loan from a Russian bank taken out in 2014.

Renaud Labaye, the general secretary of the RN group, likened the change to a small family company scaling up into a corporation. “When I was Marine Le Pen’s parliamentary assistant in 2017, we had seven MPs, maybe a dozen staffers, and managed to ask only two questions at the weekly session of questions to the government in five years,” he said in an interview. “Now we have 89 MPs and around 110 staffers, hold two of the six assembly vice-presidents, and get to ask four questions per week!”

But the momentum came to a crashing halt on Thursday, when de Fournas’s yelling led the parliamentary session to be immediately suspended. De Fournas denied any racist intention, saying he was talking about the boats and migrants rather than Carlos Martens Bilongo, his fellow MP, who was calling on France to increase co-operation with EU countries in assisting African migrants rescued from the Mediterranean Sea.

On Friday, a parliamentary disciplinary panel sanctioned de Fournas with the maximum penalty of a 15-day suspension and a temporary pay cut for “provoking a tumult” in the assembly.

Publicly, Le Pen and other RN officials fiercely defended de Fournas and accused their opponents of manipulating the episode, but in private some admitted the MP’s words were “catastrophic” and “lacking humanity”.

It is too soon to know what impact the outburst could have on public opinion. Before it occurred, the RN had been tied with the Greens as the most popular political party in France, according to a recent Ifop poll, a 12-point progression since 2017. Le Pen herself regularly ranks in the top three most popular politicians in France, and Bardella recently cracked the top 15.

During the party congress on Saturday, Bardella also defended de Fournas, and vowed to strictly regulate immigration and reserve social welfare programmes such as housing subsidies for French citizens.

“The vast majority of people in France is with us and approves of such policies,” he said.

“We are only one step away from power” he concluded. “The last efforts are ahead of us that will lead to a change in leadership that the country and the French so need.”