One of Emmanuel Macron's most loyal cabinet ministers announced on Tuesday he would step down by next year, compounding doubts surrounding the French president's administration.

Speaking to France's L'Express magazine, Interior Minister Gerard Collomb said he would quit the government after next year's European elections and run for election as mayor of Lyon in 2020.

"The local elections are still far away — I will run in Lyon if I don't get diagnosed as seriously ill anytime before that," Collomb said in jest. "I won't be interior minister right up until the last moment. After a certain amount of time it would be better to be totally free for the campaign."

The next European parliament votes will take place in May 2019.

The loss of his interior minister will only pile on the misery for Macron, whose approval ratings have plunged from around 60 percent immediately after his election to just 30 percent within 16 months.

Collomb's announcement also comes just three weeks after Macron's popular Environment Minister Nicolas Hulot resigned saying he felt "all alone" while trying to advance green policies in the government. The following week, Sport Minister Laura Flessel also stepped down citing personal reasons but insisted she continued to support the president.

Collomb spent his political career as a member of the French Socialist party but was wooed by Macron's centrist "Republique En Marche" (Republic on the Move) party in the run up to last year's election. Since then, the interior minister has described the president as "almost a son" and adamantly defended the government's pro-business policies.

Read more: French President Emmanuel Macron vows 'bold and courageous' decisions to cut public spending

Supporters and critics and weigh in

Macron's office sought to play down the significance of Collomb's impending departure, saying the 71-year-old veteran lawmaker had made no secret of his love for the city of Lyon, where he had served as mayor from 2001 to 2017.

"The president will reorganize the team when he deems it necessary," the Elysee Palace said in a statement.

Opposition critics, however, were quick to seize on the case. Eric Ciotti of the conservative Republicans likened Collomb's exit to "fleeing the Titanic," adding that it was untenable for him to combine his personal preparation for the mayoral race with his duties as interior minister. 

Read more: Emmanuel Macron leaves France's suburbs in the lurch

Guillaume Peltier, another senior member of the Republicans party, said "France deserves a full-time interior minister, not a man who's only thinking about himself and is just doing the job part time."

The spate of cabinet resignations come on the back of Macron's first major presidential scandal, after his former bodyguard Alexandre Benalla this summer roughed up protesters while wearing a police helmet.

Collomb became embroiled in the scandal after it emerged he knew about the incident but decided it was not his job to pass the information on to prosecutors. Benalla was later charged with assault.

dm/msh (AFP, Reuters)