The CIA didn't manufacture evidence about WMD in Iraq. The CIA's analysts provided heavily qualified evidence of thin possibilities of a continued chemical weapons program in Iraq. The Bush government was intent on attacking Iraq, had a number of reasons for wishing to do so, all flimsy, and they settled on the WMD because they believed that was the easiest to sell to the public, based on their intelligence. When they presented the CIA memo as justification for believing in the presence of WMD they redacted all the many qualifiers  to fit their agenda. Congress concluded that the Bush administration had overstated the case that was provided by the intelligence. 

This wasn't a case of politicized intelligence, rather, it was a case of a Republican President trying to massage or ignore the nuance of intelligence he was presented with to fit his own ends, much like Trump is doing now.

For more information read the following:

http://wapo.st/2jkECHI

http://bit.ly/1Ewn3U9