(CNN) -- Hate groups have intensified their rhetoric in recent months, but this new energy hasn't necessarily translated to an increase in the rate of hate crimes in the U.S., according to some researchers.

An FBI investigator looks over gunshot holes in the door of the U.S. Holocaust Museum on Thursday.

They also say that many white supremacist groups have been energized by a sour economy and the election of a black U.S. president.

"The traffic [on online hate discussion groups] has really been high, and there are more people who feel their voice isn't being represented," said Randy Blazak, associate professor at Portland State University in Oregon and director of the Hate Crime Research Network.

"I've heard white people say whites are being fired from their jobs because they're white, and that there's going to be a new left-wing regime that will restrict people's rights," Blazak said.

The 88-year-old Maryland man charged in Wednesday's fatal shooting at the U.S. Holocaust Memorial Museum in Washington has a long history of ties to white supremacist groups and anti-Semitic views, according to an FBI criminal complaint in the case.

A Web site attributed to the suspect, James von Brunn, proclaims itself "a new, hard-hitting expose of the Jew conspiracy to destroy the white gene-pool."

Authorities have not mentioned a motive in the shooting.

The number of active hate groups in the United States rose from 602 in 2000 to 926 in 2008 -- an increase of 54 percent -- according to the Alabama-based Southern Poverty Law Center. Watch former federal official discuss U.S. hate groups »

The center and other researchers caution that some of the increase could be due to the splintering of larger groups. Still, hate groups' activity and vitriol on Web sites have spiked in recent months, according to Brian Levin, associate professor and director of the Center for Study of Hate and Extremism at California State University, San Bernardino.

"Each person connected to these groups appears to be more riled up and more active," Levin said.

That view was echoed by Heidi Beirich, director of research at the Southern Poverty Law Center.

"If you look at the Web site postings, this is what they're talking about: a terrible economy, immigrants taking your jobs, and having a black president," Beirich said.

President Obama's election has been a huge issue with white supremacist groups, in part because he represents in their minds a demographic shift in which the white majority in the United States is becoming slimmer, Levin added.

"Interracial marriage and interracial children are the worst thing in their world, so [the demographic shift] is a big deal for them," Levin said.

Popular opinion surveys indicate the United States is less racist than it was 20 years ago, and social change in this and other areas, including issues relating to gender and sexual orientation, have "radically changed what our culture looks like in a short period of time," Blazak said.

"If you're not on board with the social change, then you're increasingly alienated," Blazak said. "A lot of the hate movement is about slowing history down or turning it back."

The number of anti-Semitic groups, including neo-Nazis and skinheads, also has been on the rise, Beirich said.

Despite the intensified rhetoric from hate groups, there is no evidence that hate crimes in the United States jumped in 2008 from the previous year, Levin said. In fact, he said data he's collected from many jurisdictions across the country show a general stability or decrease.

Still, Beirich pointed to allegations of racism-tinged crimes related to Obama's candidacy, including crosses being burned in front of homes with Obama signs.

She cited several other recent crimes allegedly motivated by hate, including one in which police say a white man in Brockton, Massachusetts, targeted minorities in January, allegedly killing two people and raping a third after researching white supremacist groups on the Internet. The suspect pleaded not guilty and the case is working its way through the court system.

The FBI's most recent statistics for reported hate crimes are from 2007, when the agency said 7,624 such incidents were reported. That figure was down from 2006, when 7,722 incidents were reported, according to the agency. Watch how stats show no increase in hate crimes »

Hate crimes are crimes motivated at least in part by a bias against the victim's perceived race, religion, ethnicity, sexual orientation or disability, according to the FBI.

The number of reported anti-Semitic assaults and incidents of harassment and vandalism in the United States declined in 2008 for the fourth straight year, according to a report the Anti-Defamation League released last week. The number in 2008 was 1,352, down from 2007's 1,460, the league said.

However, the economic slump in 2008 "brought about an increase in rhetoric targeting Jews, with letters in newspapers and on Web sites blaming Jews for the misdeeds of a select few," Abraham Foxman, the ADL's national director, said in a statement. "Hate groups and anti-Semites used the global economic downturn to breathe new life into old myths of greedy and money-hungry American Jews, and these took on a life of their own on the Internet and in the real world."

Though the Internet is full of people spewing hate, "the vast, vast majority of [them] never do anything to act on it," said Jeffrey Toobin, CNN senior legal analyst.

"The evidence of hate speech is a very poor predictor of violent tendencies," Toobin said Wednesday on CNN's "Campbell Brown."

CNN's Stephanie Chen contributed to this report.

All About United States Holocaust Memorial Museum • Racism and Bigotry • Hate and Extremist Groups