It almost seems as though there wasn't a lot of cut-throat political debating involving radio until Docket 80-90, or at least that's when I came more aware of it. Seems like most anything the FCC sent down to Congress before that was rubber stamped. What started out as a bill to address issues surrounding non-coms ended up snowballing into legislation that did indeed pave the way for deregulation.
80-90 first saw life in 1980, yes, during the Carter years. It was the brainchild of a Democrat-controlled FCC. The debate around it became so involved and so lengthy it would be 1983 before it finally passed. Yes, by then, Reagan was president, and his appointed man Fowler was in place. But many at the time believed Fowler just wanted to get 80-90 behind him because it had consumed so much of his first two years on the job, allowing him to move on to items on his administration's agenda.
80-90 relaxed the spacing rules between FM stations so that more FMs were possible. However in 1992 (when the elder Bush was president) it was a Democrat-controlled Congress that saw fit to find a way to begin to change ownership rules, allowing companies to own more than just two stations in a market. This put the proverbial foot in the door that paved the way for the Telecommunications Act of 1996, which came under Clinton's watch (although with a Republican controlled Congress). The TA of 96 is then what opened the door wide enough to allow Clear Channel to go on its first big shopping spree.
So the truth is, a lot of politicians, both Republican and Democrat, have had their hands all over radio deregulation. If you want to look for a president on whose watch the origination of deregulation came about, you can go with Carter. If you want to blame a party for the origin of ownership deregulation, look to the Democrat-controlled Congress of 1992. If you want to blame a sitting president for the deregulatory act that busted regulation wide open, well that's Clinton.
But don't just pick up one fragment of the truth and rant on it. That schtick is already owned by Rush et. al.