In OTL, the 1936 Spanish General Election was highly polarized between the Popular Front and the various right-wing parties and resulted in a Popular Front government that won by only a slight margin (100,000 votes). The Popular Front victory was probably the most influential event that motivated the Nationalist uprising that began the Spanish Civil War.
What would have been the effect of a right-wing electoral victory ushering a conservative government into power?
In 1933, the right-wing CEDA won the most seats, but the Left threatened violence, and the CEDA settled for influence over a coalition government headed by the centrist Radical Party. When CEDA was formally brought into the government in 1934, the Socialists staged an armed rebellion, which however was ineffective.
By 1936, the Left was even more radicalized, though the failed rebellion had somewhat discredited open violence. (As the rebellion collapsed in Barcelona, the Socialist leaders there escaped through a previously dug tunnel into the sewers; this was the subject of public ridicule.) The Army was accused of massacres, largely without basis. (About 1,000 rebels and 300 soldiers were killed.) Many of the Red leaders were let off and the Party was not banned.
If CEDA wins the election, and there is another outbreak of Red and anarchist insurrection, the Army will crack down, and this time with no holding back. There will be considerable bloodshed, and probably declaration of a more authoritarian state, with the Socialists, Communists, and anarchists banned. However, I don't think the "Republican Left" will join the uprising or get banned.
There will be no Civil War. Spain will resemble Hungary, Poland, or Portugal.
Gil-Robles of CEDA would be Prime Minister. He has been described as a crypto-fascist, and also as mainly a clericalist who accepted the republican form if it didn't attack the Church. However, faced with open Red violence, he would move in a fascist direction. For instance, CEDA's youth group were called "Greenshirts", in obvious analogy.
Spain would continue under civilian rule, though, and remain neutral in WW II (IMO).
Alternately, the Left might behave itself and accept the result of the election - knowing that it couldn't win by a resort to force. That means CEDA gets a few years to roll back some of the Socialist policies enacted in 1931-1933; that had been done somewhat under the Radical government, but now would be full effect.
This could get weird down the road, as the Spanish left had three main groups: the "bourgeois" Republican Left; the "Red" Left of Socialists, Communists, Trotskyites, etc; and the anarchosyndicalist Left, which refused to vote or run for office, and was extremely violent. The anarchists would not stop their running campaign of bombings and assassinations (some of which were "black-on-black" incidents). So even if the Reds behave, Gil-Robles and the Army will still have ample justification for a harsh crackdown; and having crushed the Blacks, would they spare the Reds? Especially as the Red parties probably could not control all their members.
Do Gil-Robles and his supporters abolish elections? Or do they just rig the conditions of the next elections to exclude the Reds? Or, do they play fair, and perhaps lose power to a coalition of the Republican Left, the center, and perhaps a tamed Socialist wing?
One factor is whether the Republican Left is still led by Manuel Azana. OTL, Azana was so fanatically anti-clerical and anti-monarchical that he could barely concede that CEDA was a legitimate party, while the Reds were just fine, despite the open calls for violent revolution in their newspapers. As PM and President for the Popular Front after OTL's election, he ignored the Red moves to take over police forces and prepare for revolution - which convinced Army conservatives that a coup was required. A different RL leader, who shows he won't let the Reds run wild, could avoid that reaction.
