Hubris and self assurance is a big part of why the Jedi Order was destroyed. They knew the Clone Army stank to high heaven, but they trusted the Force and their own abilities to steer them through the quagmire of **** they were getting into. And besides what were they supposed to do? Go before the Senate and say, "Uh sorry Supreme Chancellor, but you and the Republic cant use this army that you have the authority to use. Rather you must conscript your own sons and daughters to die. And better do it quick because the Separatists already have an army capable of fighting across the galaxy."
At best they could have stalled things, but Sidious would have just had the Separatists attack the Republic, and then the Senate would have told the Jedi to **** off, and used the Clones regardless.
The Jedi couldnt even set out the war, because Sidious would have just declared the Jedi traitors to the Republic or Separatists allies. Or smeared their reputation in some other way.
The Jedi were ****ed the moment Sidious became Chancellor.
