Emmanuel Macron has appointed a new junior Europe minister to handle France’s approach to Brexit, while promoting his media adviser to government spokeswoman.

In a small French government reshuffle late on Sunday night, the president gave the European affairs role to Amélie de Montchalin, a lawmaker who was once on the right before joining Macron’s centrist party. An economist, she has worked at the European Commission as a political analyst.

Her predecessor Nathalie Loiseau quit this month to lead the European parliament campaign for Macron’s party, La République En Marche. Loiseau recently told the Guardian that Brexit was taking up half of her time in the French foreign ministry, dominating all other matters.

But de Montchalin will have a junior minister role, a slight downgrading of the position, despite France stepping up its preparations for a possible chaotic no-deal exit of the UK from the EU.

Sibeth Ndiaye – a central figure in Macron’s media operations since his outsider bid to run for president in 2017 – has been appointed to government as spokeswoman. Ndiaye, who was once a student union activist and member of the Socialist party, is a key Macron loyalist. She once told the French weekly L’Express that she had no problem with lying to protect the president.

Ndiaye is also seen as a key representative of French diversity in Macron’s close circle of advisers, who were mainly young men in suits, dubbed “The Mormons”.

France has only rarely had a woman from a minority ethnic background as government spokesperson – the last was the Socialist minister Najat Vallaud-Belkacem under François Hollande.

Macron’s former government spokesman Benjamin Griveaux quit this month in order to attempt to win the nomination for Macron’s party in the battle to become mayor of Paris next year. The digital junior minister Mounir Mahjoubi, who also wants to be mayoral candidate for Macron’s party, left government at the same time.

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Macron’s party had a solid voter base in Paris in the 2017 presidential election and now wants to unseat the city’s Socialist mayor, Anne Hidalgo. Griveaux and Mahjoubi will now begin a fierce internal battle to become mayoral candidate. Griveaux – whose time as government spokesman was marked by gilets jaunes (yellow vest) protestors forcing the entrance to his ministry with a fork-lift truck and calling him snobbish and cut off – is in the lead against Mahjoubi, who has said his working-class background means he better understands the real life of the city.

Mahjoubi is replaced as digital affairs junior minister by another Macron loyalist and advisor, Cédric O.