Real Clear Politics has this commentary by James K. Glassman, criticizing the Commission on Presidential Debates. Glassman is a former Under Secretary of State, and a proponent of “Change the Rule” and “Level the Playing Field” and its ideas for improving entry into the presidential debates. Real Clear Politics holds itself out as non-partisan and non-ideological, but commentators generally think of it as a web page that leans to the Republican/conservative side.
By coincidence, if one looks at the link, one sees in the right-hand part of the page current polls for each major party’s presidential races. If one uses the data on those polls, and applies a hypothetical 15% polling rule for determining entry into the presidential primary debates, there could be no presidential primary debates for Republicans, because either one Republican, or zero Republicans, currently polls as much as 15%. The Commission on Presidential Debates only handles general election presidential debates and won’t let candidates below 15% into their debates.