August 14, 2009 -- 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."
"And if you go and take a look at this, you will find that the Obama health care logo is damn close to a Nazi swastika logo," Limbaugh said.
Later, someone painted a swastika outside the office of Congressman David Scott of Georgia, one of Obama's supporters.
Secret Service Security Around Obama
While officials told ABC News that the President's daily threat matrix has yet to reflect a sharp increase in threats, White House officials privately admit deep concern and have told the Secret Service to keep security tight, even if Obama objects.
"I think the president has, in effect, triggered fears amongst fairly large numbers of white people in this country that they are somehow losing their country, that the battle is lost," Potok told ABC News. "The nation that their Christian white forefathers created has somehow been taken from them."
Asa Eslocker contributed to this report.