Reporting from Washington - At least one Democratic political strategist has gotten a blunt warning from the White House to never appear on Fox News Channel, an outlet that presidential aides have depicted as not so much a news-gathering operation as a political opponent bent on damaging the Obama administration. Political consultants are a staple of cable television talk shows, analyzing current events based on their own experiences working on campaigns or in government. One Democratic strategist said that shortly after an appearance on Fox, he got a phone call from a White House official telling him not to be...