As hundreds of thousands of people prepare to protest again this week against Emmanuel Macron’s unpopular plan to raise the pension age to 64, the French president’s domestic standing is at stake.

Macron, who came to power in 2017 promising a pro-business transformation of France to cut taxes and overhaul the social model and welfare system, has for months been under pressure to give some impetus to his second term in office.

He has been left severely undermined on the domestic front after his centrist grouping failed to win an absolute majority in parliamentary elections last June amid major gains for the far right and radical left.

This delicate position will be stretched to the max this week when parliament begins debating Macron’s proposals to raise the retirement age from 62 to 64 and increase the number of years of work required to claim a full pension.

Macron’s credibility at home is on the line. He is seen internationally as a perpetual crisis-manager – firefighting on the Covid pandemic, the cost of living crisis, the war in Ukraine – but centrists at home would rather he is seen as constructively leaving a domestic legacy in the face of the rise of Marine Le Pen’s far right.

Macron’s current narrative is that he wants a France that “works more” and works longer – he has introduced limits to the unemployment benefits system and more people are in work. But the pensions battle is politically risky and the hardest domestic challenge of this second term. The left accuses him of seriously misjudging the public mood and increasing social inequality in hard times.

The pensions system is a recurring flashpoint of French politics because it is seen as the cornerstone of the country’s social model.

Unlike the market-led system of the UK, France has a pensions system prized for what politicians call “solidarity between the generations” – whereby the working population pay mandatory payroll charges to fund those currently in retirement. All French workers get a state pension.

France currently has the lowest qualifying age for a state pension among major European economies and spends a significant amount supporting the system. But the active working population pay high payroll charges and see fair pensions as the bedrock of how society should work.

Macron argues that the ratio of working people to retired people is shifting as the population ages, so the only way to “save” the system is to make people work longer.

But Macron’s problem is that his changes are perceived as deeply unfair, accused of increasing inequalities and hitting low- and middle-income workers and women. Macron’s prime minister, Élisabeth Borne, has been accused of a “lack of empathy”, which she said was hurtful, and called a French Margaret Thatcher, which she said was not a compliment.

The government briefly tried to turn the pensions row into a cultural war against so-called workshy lefties. The interior minister, Gérald Darmanin, said “work is not an illness”. But this misread the mood on the street. The massive protest turnout in rural towns, not just cities, has shown real anger and suffering among key workers, from teachers and nurses to care assistants, who feel unappreciated and underpaid and are struggling with stress and poor working conditions.

Every French president for the past 40 years has in some way made changes to the retirement laws, usually amid anger in the polls and demonstrations on the streets.

But the protest movement against Macron’s pension plans has been historic: more than a million have taken to the streets in the biggest demonstrations in 30 years. Trade unions from across the political spectrum, from moderate centrists to the radical left, have taken the rare step of uniting. Polls show a majority of French people are against Macron’s changes and a majority support the protest movement.

The focus is now on parliament. Without a majority, the government must rely on the rightwing Les Républicains to back pensions changes. But this is not yet a done deal. Political horse-trading continues. This weekend, Borne reached out to the right with a concession: people who started working aged 20 and 21 could retire at 63. But Les Républicains said the move did not go far enough to win their backing.

The government is already using a special fast-track procedure to shorten parliamentary debate. It could, in theory, use special constitutional powers to force through the pension changes. But Borne, aware of the uproar and protests this could spark, has suggested it is not an option. The government has until late March to try to pass the bill by agreeing to tweaks from the right. Backing down completely and shelving pensions changes would leave Macron weakened domestically for his last four years in office.

The fact that Macron was elected against the far-right Le Pen last spring continues to haunt him. Large numbers of the people on the left currently marching against Macron’s pension changes actually voted for him as president. But they did so in order to stop Le Pen, not in support of Macron’s manifesto pledge to raise pensions. They feel Macron must therefore scrap his plans.