Among the most revealing aspects of life during the Obama presidency is the panoply of responses to a black family in the White House. What made so many of us proud of our country on Jan. 20, 2009, has increasingly provoked expressions of hatred from the far right. That is troubling, but not nearly as troubling as the behavior of conservatives who excuse, embolden or simply pretend to ignore the bigots surrounding them.

Last spring, after unruly tea party protesters on Capitol Hill were accused of spewing racial epithets at civil rights hero John Lewis, an African-American congressman from Georgia, conservatives rose up in furious denial. Where was the proof? How could anyone suggest that racial prejudice lurks behind the festering right-wing hatred of President Obama (and his family)? Anger over that episode still lingers in certain quarters, motivating the deceptively edited video attack on Shirley Sherrod and the NAACP by a website called Big Government, Inc.

Even if the alleged assault on Lewis and other black congressmen did occur, argued prominent commentators on the right, it somehow only proved that there is no racism in America worthy of concern. A writer for National Review (the conservative magazine that historically opposed civil rights legislation) confided that the whole subject made him yawn:

“That these things are even remotely newsworthy leads me to one conclusion: Racism in America is dead. We had slavery, then we had Jim Crow — and now we have the occasional public utterance of a bad word. Real racism has been reduced to de minimis levels, while charges of racism seem to increase.”

But this summer has seen several loud and ugly outbursts of very real racism — including threats of violence against the president of the United States — that go well beyond the utterance of any single word. As if suffering from a facial tic, leading figures on the right cannot seem to suppress their inner Klansman these days.

Is there any other way to explain Glenn Beck’s crazed rant comparing the Obama administration to an old movie about a society where apes and chimpanzees dominate humans? What did the Fox News host mean, exactly, when he shrieked: “It’s like the damned Planet of the Apes. Nothing makes sense!” Is there any other way to explain the grotesque new best-seller by radio host Laura Ingraham, “The Obama Diaries,” where, among other things, she depicts first lady Michelle Obama eating ribs at every meal? Why would she feel the need to describe the president as “uppity” by putting the word in the mouth of his mother-in-law? No wonder Stephen Colbert taunted Ms. Ingraham to her face for “hideous and hackneyed racial stereotyping.”

Of course, these are only two of the more egregious instances in recent weeks of social poisoning that dates back well over a year. Symptoms can be seen across the country now, even in amusement parks and church carnivals, where small children are exposed to this spiritual sickness.

At the Big Time fair held by Our Lady of Mount Carmel in Roseto, Pa., last week, a game called “Alien Attack” featured “an image of a suited black man holding a health care bill and wearing a belt buckle with a presidential seal,” at which players were encouraged to aim their popguns. Anybody who hit the cardboard figure in the head or the heart could win a prize. Irvin L. Good Jr., owner of Goodtime Amusements, who is responsible for this disgusting garbage, denied that the figure represents Mr. Obama. “We’re not interpreting it as Obama,” the inaptly named huckster told a local newspaper. “The name of the game is Alien Leader. If you’re offended, that’s fine, we duly note that.”

Meanwhile on the New Jersey shore, patrons of the Seaside Heights boardwalk could hurl baseballs at a black, jug-eared Obama figurine, winning a prize if they managed to smash it. As seen in a video posted on the Gawker website, this object closely resembles the grinning “lawn jockey” statuettes that used to festoon suburban lawns in a less decent era.

Most conservatives were late in taking responsibility for their movement’s immoral opposition to civil rights. It is time for them to step up and denounce the racism that is again disfiguring our country in their name.

Joe Conason writes for the New York Observer.