California Governor Gavin Newsom has proposed a national tax on billionaires. He believes the US government should implement such a tax. At the same time, Newsom is fighting a similar tax in his own state.

Details of his national proposal are limited, but it also includes suggestions about the government's role in artificial intelligence companies. For more information on Newsom's proposals, readers can refer to the original source, which may provide further details and context on his plans for a national billionaires' tax and government ownership in AI companies.