Longtime conservative talk show host Rush Limbaugh announced on Monday that he is fighting “advanced lung cancer.” This is a devastating blow to the conservative movement and to the millions of listeners who have tuned in to listen to Limbaugh over the last few decades.

Limbaugh has faced a good deal of criticism over the last few years for his support of President Trump, and often with good reason. But Limbaugh’s conservative legacy cannot be understated. He ushered in a new era of conservative marketing in the radio industry, completely transforming the way talk show hosts communicate with listeners and generate audiences.