Pat Buchanan claimed it in a book I read long ago. http://www.time.com/time/magazine/article/0,9171,985217,00.html
Thanks. Interesting. Buchanan may have made that claim, both he and Safire served in the Nixon administration together. Prob’ly swapped a lot of ideas in WH bull sessions. Have seen, though, a number of sites, and recall attribution prior to internet era, that Safire penned the phrase.