By 1924 Trotsky was so unpopular that he would never, ever have been able to take power, particularly against Stalin, Kamenev, and Zinoviev; those three were basically running the USSR by then and Trotsky was in no position to reverse that.
Trotsky's only small window to take power was in 1923, just before Lenin died, Lenin prepared a speech that attacked Stalin and his cohorts as reactionaries. Trotsky chose not to read it and made his own speech instead. If he had read the speech by Lenin he could've taken power. At any rate, I think Trotsky would've made a terrible leader.