And then there’s Rush Limbaugh. His rants today aren’t very different from his rants in 1993. But he occupies a different position in the scheme of things. Remember, during the Bush years Mr. Limbaugh became very much a political insider. Indeed, according to a recent Gallup survey, 10 percent of Republicans now consider him the “main person who speaks for the Republican Party today,” putting him in a three-way tie with Dick Cheney and Newt Gingrich. So when Mr. Limbaugh peddles conspiracy theories  suggesting, for example, that fears over swine flu were being hyped “to get people to respond to government orders”  that’s a case of the conservative media establishment joining hands with the lunatic fringe.

It’s not surprising, then, that politicians are doing the same thing. The R.N.C. says that “the Democratic Party is dedicated to restructuring American society along socialist ideals.” And when Jon Voight, the actor, told the audience at a Republican fund-raiser this week that the president is a “false prophet” and that “we and we alone are the right frame of mind to free this nation from this Obama oppression,” Mitch McConnell, the Senate minority leader, thanked him, saying that he “really enjoyed” the remarks.

Credit where credit is due. Some figures in the conservative media have refused to go along with the big hate  people like Fox’s Shepard Smith and Catherine Herridge, who debunked the attacks on that Homeland Security report two months ago. But this doesn’t change the broad picture, which is that supposedly respectable news organizations and political figures are giving aid and comfort to dangerous extremism.

What will the consequences be? Nobody knows, of course, although the analysts at Homeland Security fretted that things may turn out even worse than in the 1990s  that thanks, in part, to the election of an African-American president, “the threat posed by lone wolves and small terrorist cells is more pronounced than in past years.”

And that’s a threat to take seriously. Yes, the worst terrorist attack in our history was perpetrated by a foreign conspiracy. But the second worst, the Oklahoma City bombing, was perpetrated by an all-American lunatic. Politicians and media organizations wind up such people at their, and our, peril.