We should have a government of, by, and for the people. In that sense, only our elected officials should be eligible to write legislation. Currently, lobbyists write nearly all the text that goes into bills, and they represent specific corporate interests, which are very often at odds with the interests of ordinary Americans.
The President should demand that Congress clearly identify any text within a bill that was drafted by anybody other than a Congressperson or Senator. As well, the authors of those supplied portions should be identified as well as who they represents (corporations, etc.). Any bill not marked as such should be vetoed.