Röhm presented a rival faction within the party, a pillar for rivals to gather around. To quote some random Kurgan immortal challenging this kilt wearing bloke: "There can be only one". Hitler didn't want to share the light.

Röhm was also irritated that Hitler got the backing of some major bankers and industrialists. He wanted there to be another revolution in which the state would play a more central role in an anti-capitalist sense, to end monopolies and nationalise industry and land. He was the "left wing" of the nazi party. He also was one if the very few people who called Hitler by his first name and was not scared of him. He led the SA, which by 1934 numbered some 3 million men whilst the Reichswehr was limited to 100,000 under the terms of the treaty of Versailles, so was in fact a potential future threat to Hitler.