Always two there are....

[Tychu]

, I'd begin investigating the members of the Senate and their staffs, looking through order records for any indication that they are Force-sensitive. It's possible the Sith lord Dooku said was manipulating the Senate would be one the Jedi have no records on, but it's better to cover all the bases.

They tried to do that in one of the issues of Republic The one that Palpatine kills this Padawans Master then becomes friends almost like Anakin and Palps and then he kills the Padawan when the Padawan had found his Masters reports on his plans on testing medichlorians on all Senators and starting with Chancellor Palpatine. No one else in the Order knew of the plans to start testing so Palps killed him.

Its either the issue in which Valorum is "assassinated" or very close to that
Its from Last year I dont have my comics with me at this posting

[CDiehl]

It is good to know this got addressed in other sources. I only know what's in the movies, and based on them, the Jedi look very bad for not having obviously done any basic investigating, which might have revealed Darth Sidious and some of his plans.

Edit: I should add that it is possible that part of the so-called "Shroud of the Dark Side" of which Yoda spoke was the order's own arrogance, of which Sidious took full advantage. It would have been nice if Yoda or Qui-Gon had confronted them about it more.