Alberto Gonzales, the controversial US attorney-general whose competency and honesty was questioned by Republicans and Democrats alike, has announced he will resign his position as the United States' top law enforcement official. Gonzales is a longtime friend and political ally of US President George W. Bush, who defended him to the end. "His good name was dragged through the mud for political reasons," Bush told reporters. But Gonzales' announcement Monday drew expressions of relief from Republicans who saw him as a further embarrassment to a beleaguered administration burdened by the unpopular Iraq war. Democrats pledged to press ahead with their investigation into whether Gonzales improperly fired federal prosecutors in collaboration with the White House and for political reasons.