Freed from the Carlist threat, Maria Cristina immediately embarked on a campaign to undo the Constitution of 1837, provoking even greater ire from the liberal quarters of her government. Failing in the attempt to overthrow her own constitution, she attempted to undermine the rule of the municipalities in 1840; this proved to be her undoing. She was forced to name the "progressista" hero of the Carlist War, General Espartero, president of the government. Maria Cristina resigned the regency after Espartero attempted a program of reform.