Many anarchists, communists and leftists turned towards insurgent tactics as Franco implemented wide reaching authoritarian policies, with the CNT and other unions being forced underground. Anarchists would operate covertly setting up local organizations and underground movements to challenge Franco. On the 20 of December the ETA assassinated Luis Carrero. The death of Carrero Blanco had numerous political implications. By the end of 1973, the physical health of Francisco Franco had declined significantly, and it epitomized the final crisis of the Francoist regime. After his death, the most conservative sector of the Francoist State, known as the búnker, wanted to influence Franco so that he would choose an ultraconservative as Prime Minister. Finally, he chose Carlos Arias Navarro, who originally announced a partial relaxation of the most rigid aspects of the Francoist State, but quickly retreated under pressure from the búnker. After Franco's death Arias Navarro began relaxing Spanish authoritarianism.