GETTY Two liberal politicians have formed a pact to keep out Marine Le Pen

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Emmanuel Macron’s stuttering campaign was given a huge boost yesterday when his one-time rival Francois Bayrou shocked French politics by announcing he will not stand as a candidate so that he can concentrate on helping his fellow centrist get elected. Polls had indicated that Mr Bayrou, a three-time presidential hopeful, would have sucked left-wing support away from Mr Macron as a candidate, significantly weakening his chances in the first round of voting.

That scenario would have potentially opened up the way for the Front National leader to take on the scandal-hit conservative Francois Fillon, against whom she polls much more strongly when it comes to the all important final ballot. Mr Macron immediately hailed the shock development as a “turning point in the campaign”, after his own poll ratings were damaged by his controversial remarks about French imperialism.

GETTY Francois Bayrou announced he will not run for president

GETTY He will instead concentrate on boosting the chances of fellow centrist Emmanuel Macron

The 39-year-old former banker, who has never held public office, enraged many voters when he described his country’s former occupation of Algeria as a “crime against humanity”. And the latest opinion poll by Ifop shows Ms Le Pen has opened up a commanding eight point lead over him for the first round of voting, despite being embroiled in her own scandal about EU expenses. Announcing his decision not to run for president, 65-year-old Mr Bayrou said: "We are in an extremely risky situation, and to tackle this exceptional situation, I think we need an exceptional response. "I have decided to offer Emmanuel Macron an alliance. The danger is too big, we must change things.”

This is a turning point in the campaign Emmanuel Macron

Describing the move as a “sacrifice” on his part, he added: “What's at stake with this alliance is to restore hope.” Polling shows that Ms Le Pen has significantly closed the gap to both her likely rivals for the second and final round of voting, but still remains a long way off being predicted to triumph over either of them. If the run-off were held tomorrow she would secure 41 per cent of the vote against Mr Macron and 42 per against Mr Fillon, according to a weekly poll tracker. And Elabe pollster head Bernard Sananes said that although Mr Bayrou's decision not to run did not radically change the polling arithmetic, it gave the Macron's campaign a boost after it had lost some momentum recently.