MEXICO CITY (Reuters) - Mexico s Attorney General Raul Cervantes said on Monday that he presented President Enrique Pena Nieto with his resignation, as an intense political debate brews over the implementation of a new, autonomous anti-corruption system to replace his office.  In the coming days the Lower House (of Congress) will be discussing new initiatives related to the attorney general s office and in order to not further delay the laws that Mexico needs I ve decided to send Enrique Pena Nieto and the Senate my irrevocable resignation,  Cervantes tweeted. Opposition lawmakers have objected to allowing Cervantes to become the head of the new prosecutor general s office, a figure who will serve a nine-year term in a move away from the current system where the president nominates the attorney general. 