Before the mural's completion in 1940, however, Siqueiros was forced into hiding and later exiled for his direct involvement in an attempt to assassinate Leon Trotsky, then in exile in Mexico City from the Soviet Union:
In the early morning of May 24, 1940, he led an attack on Trotsky's house in Mexico City's Coyoacán suburb. (
Trotsky, granted asylum by President Cárdenas, was then living in Mexico.)
The attacking party was composed of men who had served under Siqueiros in the Spanish Civil War and of miners from his union.
After thoroughly raking the house with machine gun fire and explosives, the attackers withdrew in the belief that nobody could have survived the assault.
They were mistaken.
Trotsky was unhurt and lived till August, when he was killed with an ice pick wielded by an assassin
 Trotsky's 13-year-old grandson was shot, yet survived.
Following the attack, police found a shallow grave on the road to the Desierto de los Leones with the body of New York Communist Robert Sheldon Harte, executed by one shot to the head.
He had been one of Trotsky's bodyguards.
The theory that Sheldon was a Soviet agent who had infiltrated Trotsky's entourage, aiding in Siqueiros' attack by allowing the hit squad to enter Trotsky's compound, was discounted by Trotsky and later historians.
Siqueiros's colleague Josep Renau completed the SME mural, transforming the generator into a machine that converts the blood of workers into coins.

American-born poet and eventual fellow Spanish Civil War participant Edwin Rolfe was a great admirer of Siqueiros's "ability to function" as "artist and revolutionary".
His 1934 poem "Room with Revolutionists" is based on a conversation between ″New Masses″ editor, poet, and Left journalist Joseph Freeman (1897-1965) and Siqueiros; in it, Siqueiros is described as "a revolutionist / a painter of great areas, editor / of fiery and terrifying words, leader / of the poor who plant, the poor who burrow / under the earth in field and mine. /
His life's an always upward-delving battle in / an old torn sweater, the pockets always empty."
Before the mural's completion in 1940, however, Siqueiros was forced into hiding and later exiled for his direct involvement in an attempt to assassinate Leon Trotsky, then in exile in Mexico City from the Soviet Union:
In the early morning of May 24, 1940, he led an attack on Trotsky's house in Mexico City's Coyoacán suburb. (Trotsky, granted asylum by President Cárdenas, was then living in Mexico.) The attacking party was composed of men who had served under Siqueiros in the Spanish Civil War and of miners from his union. After thoroughly raking the house with machine gun fire and explosives, the attackers withdrew in the belief that nobody could have survived the assault. They were mistaken. Trotsky was unhurt and lived till August, when he was killed with an ice pick wielded by an assassin
 Trotsky's 13-year-old grandson was shot, yet survived. Following the attack, police found a shallow grave on the road to the Desierto de los Leones with the body of New York Communist Robert Sheldon Harte, executed by one shot to the head. He had been one of Trotsky's bodyguards. The theory that Sheldon was a Soviet agent who had infiltrated Trotsky's entourage, aiding in Siqueiros' attack by allowing the hit squad to enter Trotsky's compound, was discounted by Trotsky and later historians. Siqueiros's colleague Josep Renau completed the SME mural, transforming the generator into a machine that converts the blood of workers into coins.
American-born poet and eventual fellow Spanish Civil War participant Edwin Rolfe was a great admirer of Siqueiros's "ability to function" as "artist and revolutionary". His 1934 poem "Room with Revolutionists" is based on a conversation between ″New Masses″ editor, poet, and Left journalist Joseph Freeman (1897-1965) and Siqueiros; in it, Siqueiros is described as "a revolutionist / a painter of great areas, editor / of fiery and terrifying words, leader / of the poor who plant, the poor who burrow / under the earth in field and mine. / His life's an always upward-delving battle in / an old torn sweater, the pockets always empty."
David Alfaro Siqueiros