Actually not. They were at first, and for years, but they were eventually allowed to go pretty much wherever they wanted to, and when they gave their final report they were satisfied that they had seen what there was to see. And the accuracy of their report bears that out. But this was not what the Bush administration wanted to hear, so they simply ignored it.
But they are not guilty of the same action, which is why your assertion does not stand. The Bush administration purposely lied to justify an unjust attack on another nation. The republicans backed the Bush administration in this because they wanted just as badly to believe that what Bush was saying was true, and to attack Iraq, as he did.
The democrats capitulated in this matter because they didn't take the time to seriously evaluate the evidence and because they were too afraid to dare stand in front of the war machine and call for a re-evaluation or debate. So was the press, for that matter. It took great courage for anyone at that time to dare stand up to the war mongers once their lust for blood and profits had been set in motion. But they have at least since admitted they were wrong, and that the invasion was wrong. The republicans still can't even do that, even though most of them now realize that we were wrong to invade Iraq.