Mitre and Roca had co-operated in securing a peaceful transfer of the government from Celman to Pellegrini. Roca was inclined to favour Mitre for the presidency, but it soon became evident that the latter could not control the more radical members of the Civic Union, and that his candidacy would not reconcile all parties. February 19, 1891, an attempt to assassinate Roca was perpetrated in the streets of Buenos Aires. The spirit of mutiny grew alarmingly, and a state of siege was proclaimed; the Civic Union split into warring camps; trouble broke out in Cordoba, and successful revolutions overthrew the legal state governments in Catamarca and Santiago del Estero. Mitre and Roca formally withdrew from active political life in the hope that this might placate the dissident politicians. The candidate fixed upon by the wing of Nationals who adhered to Roca, and the moderates of the Civic Union led by Mitre, was Doctor Luiz Saenz Pena, ex-Justice of the Supreme Court. The Pellegrini government gave him its earnest support, and charges were made by the Radicals that their votes would be forcibly suppressed in the election of October, 1891. They determined to anticipate violence with violence, but, on the eve of the election in October, 1891, their leaders were imprisoned and a state of siege declared. Saenz Pena was elected, but the Radicals began to intrigue to obtain control of the provincial governments, which would enable them to force his resignation or his compliance with their wishes. Serious trouble broke out early in 1892 in the province of Corrientes, with which the Buenos Aires radicals openly sympathised. The new President quickly cut loose from the Roca wing of the Nationalist party and allied himself closely with the moderate Civic Unionists, now usually called "Mitristas." The President's own son, who had been a candidate against him, headed the faction of the Nationalist party that had renounced Roca's leadership. Revolutionary movements against the governors who belonged to the Roca faction began in several provinces. In February there were armed protests in Santa Fe against a new wheat tax; a revolt broke out in Catamarca in April; by July the Saenz Pena administration was in the gravest difficulties. San Luiz and Santa Fe rebelled, and in August Salta and Tucuman followed. It was manifest that the President was not strong enough to hold down the selfish factions who saw in the general dissatisfaction and financial distress only an opportunity to get into office by force of arms.