[1] Lefebvre became involved in the struggles of the Liberal party, was one of the founders of Le Nain jaune (The Yellow Dwarf) and contributed to the Mercure de France.

[1] During the July Monarchy Lefebvre tried several times to be elected as deputy, running for the Pont-Audemer constituency on a platform opposing King Louis Philippe.

In 1850 he help passed the bill to increase the salary of the President of the Republic, the future emperor Napoleon III.

After the coup of 2 December 1851, on 25 January 1852 he was made Minister of Public Works and a member of the Consultative Commission.

While he was minister a telegraph line was established between Turin and France, 2,000 kilometres (1,200 mi) of railways were built, and packet boat concessions were awarded for the Mediterranean Sea.