Harold Meyerson, editor-at-large for The American Prospect, and an opinion writer for the Washington Post, has this piece about top-two primaries. The linked article is from the Madison, Wisconsin daily newspaper, but the article also appeared in the Washington Post. Also, the piece appeared in The Oregonian, Oregon’s largest newspaper, on July 25.
Also, see this piece in Roll Call by Nathan L. Gonzales. Gonzales points out that Schumer doesn’t seem to know that Virginia has open primaries.