Editor's note: Since the article below was published, authorities have changed their view of an incident in Dearborn, Mich., that is mentioned. Initially, it was believed that the Michigan suspect was planning an attack based on hatred of Muslims. In fact, it turns out that Roger Stockham is an American convert to Sunni Islam, and reportedly was angry at the mosque in question because it was Shi'ite.

When even leading conservatives worry out loud about the right-wing vitriol and demonizing propaganda so commonplace in contemporary America, you've got to be concerned about where our country is headed.

This January, former President George W. Bush, speaking in a question-and-answer session at Texas' Southern Methodist University, warned that the nation seemed to be reliving its worst anti-immigrant moments. "My point is, we've been through this kind of period of isolationism, protectionism, nativism" before, he said. "I'm a little concerned that we may be going through the same period" again.

In a column around the same time, conservative commentator Linda Chavez, a Fox News analyst and former Reagan White House official, warned against new nativist efforts to end birthright citizenship. "Now, egged on by radical population control groups, some Republicans want to reinterpret the Constitution and 11 decades of jurisprudence to subvert the 14th Amendment," she wrote. "They are on a fool's errand that will do great damage to the Republican Party."

Roll Call executive editor Morton Kondracke wrote the same month that we are seeing "the Arizonification of America," a reference to the state that last year passed the harshest anti-immigrant law in memory. "It has become a state of Minuteman vigilantism, death threats against politicians and judges, talk-radio demagoguery, and bullying of Latinos and rival politicians," he said.

And neoconservative Bill Kristol, writing this February, worried about the "hysteria" in contemporary conservativism that he sees exemplified in a particularly voluble Fox News host. "When Glenn Beck rants about the caliphate taking over the Middle East from Morocco to the Philippines, and lists (invents?) the connections between caliphate-promoters and the American left, he brings to mind no one so much as Robert Welch and the John Birch Society," Kristol wrote. "He's marginalizing himself, just as his predecessors did back in the early 1960s."

Given these warnings from leading conservatives, it is not surprising that the Southern Poverty Law Center's latest count found that the number of hate groups operating in America last year had risen to 1,002 from 932 in 2009. The number of nativist vigilante groups was up, too, from 309 in 2009 to 319 in 2010. And there was truly explosive growth in the antigovernment "Patriot" movement, which added 312 new groups last year, skyrocketing 61% from 512 in 2009 to 824 last year.

As we explain in this issue, this dramatic growth of the radical right for the second consecutive year is related to anger over the changing racial make-up of the country, the ailing economy and the spreading of demonizing propaganda and other kinds of hate speech in the political mainstream.

The white-hot political atmosphere is not limited to hard-line nativist politicians, conspiracy-mongering cable news hosts, or even openly radical hate groups. During the same month when most of these conservative commentaries were written, the nation witnessed an extraordinary series of events that highlighted the atmosphere of political extremism.

On Jan. 8, a Tucson man opened fire in a parking lot on U.S. Rep. Gabrielle Giffords, Democrat of Arizona, killing six people, critically wounding the congresswoman and badly injuring another 12 people. Giffords' assailant appeared to be severely mentally ill, but he also seemed to have absorbed certain ideas from the radical right, including the notion that the federal government is evil.

Six days later, a neo-Nazi named Jeffrey Harbin was arrested in Arizona for possessing 12 grenade-like devices packed with ball bearings — "to maximize human carnage," as a federal prosecutor put it. A member of the National Socialist Movement, Harbin was heading for the border when he was arrested.

Three days after that, on Jan. 17, police in Spokane, Wash., found and defused a sophisticated anti-personnel bomb that had been hidden along the route of a Martin Luther King Jr. Day parade. Officials said they were looking into local hate groups as part of their search for the would-be mass murderer.

And on Jan. 24, police in Michigan arrested a man in a car loaded with M-80s and other explosives in a parking lot outside one of the nation's largest mosques, packed at the time with 500 mourners at a funeral. He was charged with making a terroristic threat and possessing explosives with unlawful intent.

We are living in a deeply polarized and dangerous moment, and that may be nowhere more obvious than in the state of Arizona, as Mort Kondracke pointed out.  Perhaps no one captured that better than Pima County Sheriff Clarence Dupnik, speaking at a press conference after the Tucson assassination attempt.

"[L]ook at unbalanced people, how they respond to the vitriol that comes out of certain mouths about tearing down the government," the sheriff said. "The anger, the hatred, the bigotry that goes on in this country is getting to be outrageous and, unfortunately, Arizona has become sort
of the capital. We have become the mecca for prejudice and bigotry."

Sadly, much of the country is following Arizona's lead.