Although his politics is certainly nothing like those of Corbyn, Trump is rather a lot closer to Labour's loony leftie leader than he is to the Tories. His success is based on his charisma, his ability to say what some extreme people are thinking. Corbyn is the same, only for the left (and, perhaps, a slightly smaller proportion of the population). That strong, but narrowly-focused appeal, is Trump's strength but also his weakness.
He retains a huge lead in national polls for the republican nomination, and with only a couple of weeks to go until the first vote I would be surprised if he didn't win at least one out of Iowa and New Hampshire. Can he sustain it? Possibly not, because (I would hope) the field of candidates would drop down from the current 26 to a handful for future elections, and it would be easier for the opposition to Trump to unify.
Anyway, Trump is to Cameron as Corbyn is to someone actually electable.