Leader of Madrid Regional Government Resigns MADRID - Esperanza Aguirre, the head of Madrid's regional government and one of Spain's most influential and outspoken politicians, announced her resignation on Monday for personal reasons after receiving a diagnosis of breast cancer last year. She said her surprise announcement was only partly motivated by her health problems, and that the decision was final. "There is no way back from this, this is crossing the Rubicon," she said at a press conference, as she choked back tears. Ms. Aguirre, who is 60, was at the forefront of Spanish politics for three decades, including as a former head of the Spanish Senate and as national education minister. Since 2003, she ran the Madrid region, making her arguably the most powerful regional leader within the Popular Party of Prime Minister Mariano Rajoy as well as a possible candidate to succeed him as the first female politician at the helm of the country. She will be succeeded as Madrid's regional leader by her deputy, Ignacio González. She recently opposed plans by Mr. Rajoy's government to grant early release to a member of ETA, the violent Basque separatist group, who was jailed for murder but found to be terminally ill with cancer. Ms. Aguirre also ruffled feathers because of her demands that Sheldon Adelson, the American casino tycoon, be granted fiscal and other concessions in return for his company, Las Vegas Sands, building a giant gaming and leisure resort on the outskirts of Madrid. In a statement, Mr. Rajoy paid tribute to Ms. Aguirre's "huge political trajectory" and government accomplishments.