A former Speaker of the House is addressed, and referred to as, Mr. x, not Speaker x. The current President of the United States is addressed, and referred to as, President, not Mr. x.
Do not assume other public officials, candidates for public office, radio or TV news hosts, newspaper reporters, or others know correct forms of address. Look it up yourself. It’s fun!
You will find authority for these pronouncements in any number of respected forms of address manuals, e.g. to name only two:
1) Protocol School of Washington website, How to Address Former Officials
2) My favorite print source: “Protocol: The Complete Handbook of Diplomatic, Official and Social Usage,” Written by Mary Jane McCaffree, Pauline Innis and Richard M. Sand, Esquire