increasing fears for President Obama's safety because of the plethora of nutcases -- many of them in fact mentally ill -- who are crawling out of the woodwork and threatening Obama and anyone associated with him:

Experts who track hate groups across the U.S. are growing increasingly concerned over violent rhetoric targeted at President Obama, especially as the debate over health care intensifies and a pattern of threats emerges.

The Secret Service is investigating a Maryland man who held a sign reading "Death to Obama" and "Death to Michelle and her two stupid kids" outside a town hall meeting this week. And in New Hampshire, another man stood across the street from a Presidential town hall with his gun on full display.

Los Angeles police officers apprehended a man Thursday after a standoff with him inside a red Volkswagen Bug car in Westwood, CA – the latest disturbing case even though officials said the man had mental problems.

"I don't think these are simply people who are mentally ill or off their rocker," Mark Potok, director of the Intelligence Project at the Southern Poverty Law Center, told ABC News of those behind the threats. "In a very real sense they represent a genuine reaction, a genuine backlash against Obama."

Experts say a sharp growth in so-called militia groups that helped spawn a wave of domestic terrorism in the 1990s – and are now using YouTube, rock music and the Internet to recruit members and spread hate and fear - shouldn't be ignored.

"It's certainly a scary time," said former FBI agent Brad Garrett, now an ABC News consultant. Garrett said the Secret Service "cannot afford to pass on anyone," and he believes "they really do fear that something could happen to [Obama]."

Garrett said statements like one recently made by controversial radio host Rush Limbaugh comparing a logo for the White House plan to a Nazi symbol "legitimizes people who are on the edge to go do something or say something."

Naturally, the right is full-throated whine about people making this very logical connection: Yesterday on his show, Glenn Beck repeated the standard whine that "left is trying to silence me." No; we just want people like Beck to live up to the immense responsibility that comes with having those powerful media megaphones they hold.

Often we hear the excuse that the problem is simply the fact that these people are mentally ill crazies who would be doing something crazy anyway.

This is, of course, a complete cop-out. It ignores, in fact, the cold reality that violence, even by the mentally ill, does not occur in a vacuum. When people become the subject of a relentless campaign of demonization -- especially by the use of grotesque smears that make them out to be monsters and provably false "facts" that have the concrete effect of unhinging people from reality -- it will only be a matter of time before the lethal violence breaks out.

And while the concern for Obama is well-placed -- he is, after all, the focus of all this hatred -- there is only a remote likelihood of anyone actually succeeding in harming him, since he is very well protected indeed. What's far more likely, in fact, is that some innocent bystanders in his vicinity will be harmed -- or, moreover, that the crazies will decide that instead of harming Obama, they will take out their hatred on his supporters.

This was the thinking, after all, of Jim David Adkisson, the Knoxville church shooter. Recall this passage in his manifesto:

This was a symbolic killing. Who I wanted to kill was every Democrat in the Senate & House, the 100 people in Bernard Goldberg's book. I'd like to kill everyone in the mainstream media. But I know those people were inaccessible to me. I couldn't get to the generals & high ranking officers of the Marxist movement so I went after the foot soldiers, the chickenshit liberals that vote in these traitorous people. Someone had to get the ball rolling. I volunteered. I hope others do the same. It's the only way we can rid America of this cancerous pestilence.

The right-wing crazies popping up almost daily, thanks to right-wing fearmongers, are very real cause for concern about Obama's safety. But we should also be concerned about our own.