She was manipulated in EP I, Palpatine used her to vote against Valorum. If we add the EU her election as queen was nothing but Palpatine's scheme, of course he underestimated her a bit.
Ok yes she was tricked on that part , but Valorum was an incompetent moron who didn't know what the hell was going on. As for her rise to queen...ehhh yes and no I wanna say on that, she was already popular and opposed Veruna's policies though I won't say that Palpatine didn't give her an extra leg up.
Am speaking more of the manipulation thing during EP 3, not so much the first two.