Why did the mexican government set up a federal republic?

On November 7, 1823, the constituent congress opened, approving the Basic Law on January 31 of the following year, which was to remain in force until the adoption of the constitution. The law confirmed that the Mexican nation is forever free and independent of Spain or any other power. Of particular importance was Article 5, which stated that "a nation shall adopt a republican, federal, popular, representative form of government. On the same day, Congress addressed to the people with an appeal that characterized the adoption of the Basic Law as the end of the revolution. "This is a national banner," the appeal said, around which all patriots should unite, because if before they could have different views on the form of government, they are now obliged to obey the opinion of the vast majority expressed by the deputies elected for that.

In this country, the idea of federalism from its inception had a pronounced political connotation, since federalism was the 'banner' of the liberal party, and centralism represented the party of conservatives - the two largest political parties in the country. It was quite obvious that, depending on the results of the political struggle for power, the country should develop along the path of federalism or centralism.