The Hill, a newspaper intended to be read by congressional staffers and others interested in politics and the federal government, has this op-ed by Professors Larry Diamond and David C. King about the Commission on Presidential Debates. Diamond and King rebut the arguments used by the CPD in defense of the 15% polling requirement for entry into the general election debates.
If a reader clicks on the link, the article appears, then it goes into semi-darkness for about 12 seconds, and then it suddenly becomes readable, so wait patiently.