He served as the President of the Senate of Uruguay from 1841 to 1845. Suárez served in the office designated as President of Uruguay from 1843 to 1852, during the Uruguayan Civil War. However, his effective rule was limited to the old city of Montevideo; historians remember this rule as "Gobierno de la Defensa" (Defense Government), as he was defending the city during the Great Siege of Montevideo, which in turn was led by Manuel Oribe, who ruled over the rest of the country.