Marine Le Pen’s far-right, anti-immigration party is in reach of becoming the biggest political force in the French parliament after a historically high showing in the first round of snap parliament elections. The left and centrists immediately began to call for tactical voting to try to stop the far-right before next Sunday’s final round runoff, after exit polls indicated the National Rally (RN) had won about 34% of the national vote share with the leftwing alliance in second place and Emmanuel Macron’s grouping trailing in a distant third. The RN took about 12m votes – almost three times the 4.2m it took in the last parliamentary election in 2022. Speaking after the polls had closed, Le Pen said French people had shown “in an unambiguous vote … their wish to turn the page on seven years of the disdainful and corrosive [presidency]” of Macron. The president’s centrists, she said, had been almost “wiped out” by the RN, which was now hoping to increase its 88 seats in parliament to a majority of 289. This is still seen as a steep challenge, but if it happens in next Sunday’s decisive second round of voting, it will be the first time in French history that a far-right party has won a parliamentary election and forms a government. In that scenario, Macron – who called the election three weeks ago after losing to the RN in the European elections – would have to share power. Equally, the RN could win the largest number of seats but fall short of a majority. Macron could then find himself with a hung parliament unable to govern the EU’s second biggest economy and its top military power. The New Popular Front (NFP), a leftwing coalition formed in an attempt to hold back the far right, was thought to have taken about 29% of the vote share. “We have one week to stop the far right coming to power, all progressives and humanists … have to mobilise behind the New Popular Front,” said Clémentine Autain of the leftwing France Unbowed party before the second-round election race next week. Macron’s centrist alliance fared badly, with exit polls showing it having won between 20.5% and 23% of the vote. It was the biggest grouping in parliament, but it could now could lose more than half of its seats and be relegated to third place. The national vote share indicates the broad trend of voting, but does not predict the exact makeup of the 577-seat parliament, which will only become clear in the final round on 7 July. Most constituencies will now go to runoffs. A record number of these will be three-way runoffs. On Sunday night, Jordan Bardella, Le Pen’s protege and party president, said he wanted to be the “prime minister of all the French”. But in cities such as Paris, Lyon, Lille, Nantes and Strasbourg thousands took part in street demonstrations against his party. Large crowds gathered at the Place de la République in the capital, where leading figures in the left alliance spoke out against the far right. Bardella has said he will only become prime minister if his party wins an absolute majority. He has ruled out trying to form a minority government and neither Macron nor the NFP leftist group will form an alliance with him. “I will be a ‘cohabitation’ prime minister,” he said, referring to the fact that Macron will remain president. He said he would be “respectful of the constitution and of the office of President of the Republic, but uncompromising about the policies we will implement.” The RN’s chances of winning power will depend on the political dealmaking made by its rivals over the coming days. In the past, the traditional right and leftwing parties have struck agreements to stand down candidates from the runoffs to avoid splitting the vote against the RN. But the tactical voting strategy known as the “republican front” to block the RN is less certain than ever. In a written statement, Macron called on voters to rally behind candidates who are “clearly republican and democratic”, which, based on his recent declarations, would exclude candidates from the RN and from Jean-Luc Mélenchon’s France Unbowed, but not candidates representing the NFP’s more moderate leftwing parties. In an address, the prime minister, Gabriel Attal, echoed that appeal, saying that with the RN at the gates of power, runoff candidates in third place should withdraw. “Not one single vote must go to the National Rally … The stakes are clear: to prevent the National Rally from having an absolute majority,” he said. Mélenchon said the left alliance would withdraw all its candidates who came third in the first round, saying: “Our guideline is simple and clear: not a single more vote for the National Rally.” Several RN MPs were elected in the first round, including Marine Le Pen. In northern France, one of the most popular figures on the French left – the head of the Communist party, Fabien Roussel – was knocked out in the first round by the RN candidate, Guillaume Florquin. The turnout of more than 69% – way above the turnout in 2022 polls of just 47.5% – was the highest in almost 40 years in an increasingly polarised country, where Macron had said that a win by either the far right or hard left could lead to “civil war” in France. Risk analysis firm Eurasia Group said the RN looked “likely” to fall short of an absolute majority. France was facing “at least 12 months with a rancorously blocked National Assembly and – at best – a technocratic government of ‘national unity’ with limited capacity to govern”, it added. For decades, the Front National party co-founded by Le Pen’s father, Jean-Marie Le Pen, was regarded as a danger to democracy that promoted racist, antisemitic and anti-Muslim views. Centrist and leftwing politicians attempted to remind voters of the history of the 52-year-old party, which at its start included in its ranks former members of a Waffen-SS military unit under Nazi command during the second world war. But the renamed party surged after Marine Le Pen’s years-long public relations drive to normalise its policies and detoxify its image. The anti-immigration party has, however, kept its traditional doctrine once known as “France for the French”, or “national preference”, which it has renamed “national priority”. It means that French citizens would, if the RN were in power, be given priority over non-nationals for jobs, social welfare assistance and housing. The party has pledged to bar dual nationals from certain strategic state jobs in France. It wants to scrap nationality rights for children born and raised in France by foreign parents. Macron stunned and bewildered his own government and supporters with his decision this month to dissolve parliament and call snap elections after his centrist, pro-European grouping was trounced by the RN in EU elections. He argued that he was calling the vote to “clarify” the French political landscape.