French president Emmanuel Macron has warned his supporters not to assume that he will win a second term in this month’s election, suggesting that one of his far-right rivals could defeat him.

In his only big rally of the campaign, the French leader pointed to his own victory in 2017 and the UK’s vote for Brexit the previous year as examples of unexpected political outcomes.

“The extremist danger today is even greater than it was a few months ago, a few years ago,” he told supporters who gathered in an auditorium at La Défense just outside Paris on Saturday.

“Don’t believe the commentators or the opinion polls who say it’s impossible, unthinkable, who say ‘the election is already won and it’ll all be fine’. Look at us, look at you, five years ago. People said it was impossible. Look at Brexit and so many elections where the result seemed improbable but did actually happen.” 

Opinion polls project that Macron will come top in the first round of voting next weekend, ahead of far-right candidate Marine Le Pen. He is then expected to win against her in the second and final round two weeks later as he did five years ago, but this time the polls predict a much narrower margin of victory.

According to the latest Ipsos survey released on Saturday, Macron would receive 26 per cent of first round votes, followed by Le Pen on 21 per cent and the far-left candidate Jean-Luc Mélenchon on 15.5 per cent. In the second round, Macron would beat Le Pen by 53 per cent to 47.

In 2017 Macron campaigned as a candidate who was “neither right nor left”. He had never held elected office and was hailed as a breath of fresh air. He crushed the two main political movements that had held the presidency for the past six decades: the Gaullists, now represented by the conservative Les Républicains, and the Socialists.

This time, however, he is seen as part of the establishment after five years in the Elysée Palace.

Macron’s poll ratings jumped in the early weeks of the Ukraine war because he was seen as a leader in a time of conflict. However, that bounce has quickly faded, while his prominent role in international efforts to impose sanctions on Russia and persuade Vladimir Putin to withdraw his forces has limited his time on the campaign trail at home.

Some voters among the left and the Greens who backed him last time also say they dislike what they perceive as his rightwing economic policies and his reputation for arrogance.

In his speech on Saturday, Macron emphasised his achievements — including cutting unemployment to the lowest level for more than a decade — and promised to aim for full employment in the next five years.

He also sought to burnish his credentials in the fight against climate change, arguing that with nuclear power, investment in renewables and energy saving measures France “will become the first great nation to exit from fossil fuels”. 

Macron emphasised his commitment to Europe and the EU — in contrast to both Le Pen and Mélenchon — and said a Europe of joint defence, environmentalism and regulated capitalism was an important counterweight to the superpower “duopoly” of the US and China and the “great disorder” of geopolitics.

“The world of peace that we used to think was eternal, the world of continuous forward progress that we used to think was unstoppable, all this seems to be falling apart in front of our eyes,” he said.

“What we are living through is a kind of great disorder,” Macron said, citing the troubles of the natural world and the environment, of capitalism and the rise of inequality, of religious extremism and conspiracy theories, and “geopolitical disorder with the return of wars and dreams of empire, and the spectre, perhaps, of global armed conflict”.