As soon as the Viet Minh overthrew the government, the Trotskyists were trying to start their own "revolution" in Vietnam. Keep in mind that the Communist party had only recently been united (it had split into about 3 factions), the Viet Minh were still trying to fully overthrow the imperial government and were fighting soldiers from Japan, France, China and reactionary Nationalist Vietnamese forces basically all at once. And in this fragile situation the Trotskyists could think of nothing better to do than sabotage the efforts of Comrade Ho Chi Minh and the Vietnamese people.
"Stalinists" weren't popular simply because nobody had really heard of Communism. It was against the imperialist law to be a revolutionary which is why Ho Chi Minh has become notorious for the amount of aliases used throughout his life (he frequently changed his name to evade the Sûreté, French secret police).
In Duiker's book, mentioned above by dodger, it is said that Stalin and the SU played little to no role in the first stages of their revolution but Comintern policy did. Ho Chi Minh was of course a Comintern agent and had studied briefly at the "Stalin School" in the Soviet Union. They met several times after the August Revolution: the SU agreed to aid Vietnam against France and was the first to recognize the new revolutionary government.