The election is seen as an immense gamble for Macron
The election is seen as an immense gamble for President Emmanuel Macron. AFP

French President Emmanuel Macron and his allies were on Monday beginning a week of intense campaigning ahead of the second round of legislative elections to prevent the far right in a historic first from taking an absolute majority and control of government.

The far-right National Rally (RN) party of Marine Le Pen won a resounding victory in the first round of the polls Sunday, with Macron's centrists trailing in third behind a left-wing coalition.

But the key suspense ahead of the second round on July 7 was whether the RN would win an absolute majority in the new National Assembly, as well as the largest number of seats.

That would enable the party of far-right figurehead Le Pen to be certain of taking power and for her protege Jordan Bardella, 28, to become prime minister.

French Prime Minister Gabriel Attal, who is likely to be forced to resign after the second round, warned that the far right was now at the "gates of power". The RN should not get a "single vote" in the second round, he said.

"We have seven days to spare France from catastrophe," said Raphael Glucksmann, a key figure in the left-wing alliance.

Macron had stunned the nation and baffled some allies by calling snap polls after the RN trounced his centrist forces in European Parliament elections this month.

Projections from prominent French polling firms gave the RN 33.2-33.5 percent of the vote, compared to 28.1-28.5 percent for the left-wing New Popular Front alliance, and 21.0-22.1 percent for Macron's centrist camp.

The polling agencies projected this would give the RN a majority of seats in the 577-seat National Assembly after the second round. But it was far from clear the party would garner the 289 seats needed for an absolute majority.

The projections varied sharply, with Ipsos forecasting 230-280 seats, Ifop 240-270 and Elabe the only organisation to put it in the range of an absolute majority of 260-310 seats.

In a statement, Macron called for a "broad" alliance against the far right in the second round, which will see run-off votes between two or three candidates where there was no outright winner in the first round.

The leftwing alliance and the president's camp will be hoping that tactical voting to prevent RN candidates winning seats will leave it short of the absolute majority.

With the French facing their most polarising choices in recent history, turnout soared to 65 percent, way above the turnout in 2022 polls of just 47.5 percent.

Macron said the high turnout in the first round spoke of "the importance of this vote for all our compatriots and the desire to clarify the political situation".

The arrival of anti-immigration and eurosceptic RN in government would be a turning point in French modern history: the first time a far-right force has taken power in the country since World War II, when it was occupied by Nazi Germany.

"Nothing is won and the second round is decisive," Le Pen, who has long worked to distance the party from its extremist origins, told supporters.

"We need an absolute majority so that Jordan Bardella is in eight days named prime minister by Emmanuel Macron."

Bardella said he wanted to be the "prime minister of all French".

This would create a tense period of "cohabitation" with Macron, who has vowed to serve out his term until 2027.

Bardella has said he will only form a government if the RN wins an absolute majority in the elections.

The alternative is months of political paralysis and negotiations to find a solution for a sustainable government that can survive no-confidence votes.

Hard-left leader Jean-Luc Melenchon said Macron's centrist alliance had suffered a "heavy and undisputable" defeat in the snap polls.

Risk analysis firm Eurasia Group said the RN now 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.

Macron's decision to call the snap vote sparked uncertainty in Europe's second-biggest economy. The Paris stock exchange suffered its biggest monthly decline in two years in June, dropping by 6.4 percent, according to figures released on Friday.

French daily Liberation urged voters to unite to halt the march of the far-right. "After the shock, form a block," the newspaper said on its Monday front page.