Who was the Spanish ambassador that criticized McKinley?

Enrique Dupuy de Lôme wrote "... McKinley is: weak and catering to the rabble, and, besides, a low politician, who desires to leave a door open to me and to stand well with the jingoes of his party." in his letter. The incident is known as the De Lome Letter and acted as one of the primary triggers of the Spanish-American War.