 Castro became critical of the corruption and violence of Grau 's regime , delivering a public speech on the subject in November 1946 that earned him a place on the front page of several newspapers . In contact with members of student leftist groups – including the Popular Socialist Party ( Partido Socialista Popular – PSP ) , the Socialist Revolutionary Movement ( Movimiento Socialista Revolucionaria – MSR ) and the <unk> Revolutionary Union ( Unión <unk> Revolucionaria – UIR ) – he grew close to the UIR , although biographers are unsure whether he became a member . In 1947 , Castro joined a new socialist group , the Party of the Cuban People ( Partido Ortodoxo ) , founded by veteran politician Eduardo Chibás ( 1907 – 1951 ) . A charismatic figure , Chibás advocated social justice , honest government , and political freedom , while his party exposed corruption and demanded reform . Though Chibás lost the election , Castro remained committed to working on his behalf . Student violence escalated after Grau employed gang leaders as police officers , and Castro soon received a death threat urging him to leave the university ; he refused and began carrying a gun and surrounding himself with armed friends . In later years Castro was accused of attempting gang @-@ related assassinations during this period , including that of UIR member Lionel Gómez , MSR leader Manolo Castro and university policeman Oscar Fernandez , but these charges remain unproven . 
