Simultaneously, he has been attacking his erstwhile Republican rivals with a viciousness not seen in American politics since the early 19th century. The timidity of the rivals' responses to personal attack and, more importantly, their failure to challenge his bigotry - indeed, their joining his call for mass deportation - paints the Republican candidates collectively as a Confederacy of Dunces.
Republican insiders are worried about the damage he may be doing to the Republican brand. As George Will, the acknowledged mandarin of conservative columnists, laments: "Every sulfurous belch from the molten interior of the volcanic Trump phenomenon injures the chances of a Republican presidency."
If the outsize personality and the antics of Donald Trump were injurious only to the image that my former party seeks to present, it would merely be a matter of chickens coming home to roost. Ronald Reagan succeeded in presenting government, itself, as the problem in the continuing effort of conservatives to roll back the welfare state of Franklin Roosevelt and Lyndon Johnson.
In the last three administrations, partisanship has superseded governance and the geniality of Reagan has morphed into the incivility of Republican representative Joe Wilson's shouting "You lie!" as President Barack Obama spoke to Congress in 2009.
Trump's ugliness, which surpasses his confreres' and forces them into a race to the bottom, is then payback. The appeal he generates is among the disaffected - those Republicans who have been trained to distrust government and to whom all politicians, including their own, are untrustworthy. To these folks, Trump's unbridled tongue and unscripted impulse looks like authenticity.
More worrisome is his appeal to the further extreme fringe. Evan Osnos reports in the New Yorker that Trump has had particular resonance with the fearful and frustrated, people threatened by racial diversity. He has drawn praise from ex-Klansmen like David Duke, while The Daily Storm, a neo-Nazi website, urged its followers "to vote for the first time in our lives for the one man who actually represents us".
The problem for the Republicans and the rest of the United States is not so much Trump himself, but his effect on the political climate in which the previously unspeakable is granted respectability.
What is truly of concern is the passion he has generated within the community of white supremacists, racial fanatics, survivalists and others threatened by a sense that the increasing diversity of America's demographics means that their current white privilege will be diminished.
The virus of xenophobia, of racial hatred and religious intolerance lies dormant within a sector of the populace in developed countries everywhere. Once activated, who knows how far that infection will spread and how virulent it may become before it is contained once more.
Jay Kuten is an American-trained forensic psychiatrist who emigrated to New Zealand for the fly fishing. He spent 40 years comforting the afflicted and intends to spend the rest afflicting the comfortable.
