A run-down of what Palpatine has done in the prequels so far:
Pushed the Trade Federation (posing as Sidious) to blockade Naboo, knowing it would lead to hostilities. He also knows the Senate would be paralyzed by bureaucracy, so he is able to force a vote of "no confidence" in the current Chancellor, knowing he'd get the sympathy vote because he is from Naboo. So, now he's gone from ordinary senator to Chancellor of the Senate.
In Ep. 2, he cons Jar-Jar into convincing the Senate to grant Palpatine "emergency powers", which includes the use of clone army. Palpatine also delivers this awesome quote:
What a dick! You know he's lying through his teeth.
Meanwhile, he has Dooku doing his dirty work to sign up various systems for war against the Republic. He even has the schematics in place for the construction of the 1st Death Star.
By the end of Ep. 2, he's started the wheels in motion for galactic war in order to solidify his power. And he did it right under the noses of the Jedi Council, who are completely unaware of what is going on.
The guy is pulling everybody's strings (as both Palpatine and Sidious) in order to rise to power. And that's not even taking into account what he'll do in Ep. 3 (which includes showing off his Force powers).