He has made frequent appearances on Fox News, and in 2018 wrote an opinion piece for Fox News's website in which he attacked the investigation by Special Counsel Robert Mueller, alleging that Mueller and "Democratic-leaning lawyers" were acting improperly in trying to prepare a charge of obstruction of justice against Donald Trump. In these articles, Penn did not disclose that his firm had previously done work for Trump in the 1980s. Penn has used the term "deep state" to refer to what he characterizes as Democratic operatives within the government who seek to undermine and sabotage Trump's presidency.