MEXICO CITY — The president of Mexico said Tuesday that he was submitting a proposal to Congress to legalize same-sex marriage, as Mexico presses forward with breaking long-held taboos in Latin America.

Argentina, Uruguay and Brazil already allow same-sex marriage, and Colombia’s high court declared last month that gay couples have a constitutional right to marry. With the addition of Mexico, more than 70 percent of Latin Americans now live in countries where same-sex marriage is permitted.

President Enrique Peña Nieto of Mexico said his two bills would change the Constitution to incorporate the right for same-sex couples to wed and reform the federal civil code to assure marriage equality.

Those changes would turn into law a ruling last year by the nation’s Supreme Court that it was unconstitutional for states to ban same-sex marriage. In practice, though, the effect of the ruling was to legalize gay marriage without requiring Mexico’s states to rewrite their marriage laws.