Not trying to get off topic, look at what Palpatine is doing. Obi-Wan gave the reasons why the Jedi grew to distrust the Chancellor and interference in Jedi affairs was the last straw on top of attaining executive powers to keep him in office. Maybe they thought Sidious was influencing everyone in the Senate, especially at top, all the while not know just who Sidious really was. Terrible. No one wouldn't expect Mas Amedda. He's not even a politician. I think the Jedi are looking for a politician in particular. They probably already have an inkling that Sidious is human, not alien so they are looking for a human politican as well but have no idea where to look.