March 22, 2010 -- The Secret Service is investigating two Twitter users who, apparently angered by the passage of the health care reform bill, took to the Internet Sunday to call for the assassination of President Obama.

"ASSASSINATION! America, we survived the Assassinations and Lincoln & Kennedy. We'll surely get over a bullet to Barrack Obama's head," wrote one Twitter user, who goes by the handle Solly Forell, and identifies himself as a conservative blogger and "'authentic' African American."

Soon after the first post, Forell tweeted another message actively encouraging someone with a "clear shot" to kill the president.

"The next American with a Clear Shot should drop Obama like a bad habit. 4get Blacks or his claims to b[e] Black. Turn on Barack Obama," he wrote on the messaging Web site.

The Secret Service investigates any perceived threats to the president or calls for his assassination.

"We are aware of the comments and are taking the appropriate investigative action. We respect the right of free speech, but in such instances we have a right and an obligation to ask questions and determine intent," the Secret Service told ABC News.

'I'd Shoot Him Myself'

Another Twitter user who called himself THHEE_JAY and was identified as Jay Martin, tweeted "You Should be Assassinated!! @Barack Obama."

Martin, who is black, followed his tweet, writing "If I lived in DC. I'd shoot him myself. Dead f***ing serious."

As of Monday morning Martin had 1,575 subscribers to his feed and Forrell had just 321 -- both modest by Twitter's standards.

Forell's name is attached to several makeshift conservative blogs, Anybody But Barack Obama2012 and the Audacity of Hype.

Health Care Bill Prompts Assassination Threats on Twitter

According to a Google profile, Forell is also author of the blog Barack Obama Was an American Electorate Mistake, as well an upcoming "golf self-help book" and a work of fiction to be titled "The Organization." Both books, Forell said on his profile, will be published under his given name.

Forrel did not respond to email messages from ABCNews.com.

Soon after their posts went viral and were picked up by blogs and received messages alerting them that they would likely be the subjects of federal investigations, both men attempted to retract their statements.

"Let us all renounce the harsh rhetoric about POTUS," said a tweet on the Forell feed. "Several including myself have used inappropriate language. Let's remain civil!"

"For the record," said a tweet on Martin's feed, "I NEVER said I would do harm to the president. I simply expressed my anger."

Twitter removed the offending posts from the Solly_Forell feed, but despite a statement from the company to the blog jezebel.com that the account would be dismantled, it continued to operate on Monday.

"We have removed this profile due to violation of Twitter's Rules, specifically listed under "Content Boundaries and Use of Twitter": *Unlawful Use: You may not use the service for any unlawful purposes or for promotion of illegal activities," Twitter said in the statement.

"It is against the Twitter Terms of Service to use the service to commit illegal acts. Threatening the life of the president (or president-elect) is a federal offense under Title 18, USC, section 871. All accounts in violation of our Terms of Service are permanently suspended and we report to legal authorities accordingly."

Twitter did not immediately return messages for comment by ABC News.com.

The tweeted threats come on the heels of increasingly-heated rhetoric by some conservatives aimed at Democratic lawmakers working on health care reform, even as the Secret Service says threats against the president are declining.

On their way into the House over the weekend, protesters yelled racial and homophobic epithets at entering Congressmen.

Health Care Bill: Threats Against Obama

Earlier this month Secret Service Director Mark Sullivan told a House committee that assassination threats against the president had declined sharply since their peak during the 2008 election.

"We have a program area that is just dedicated to protective intelligence I believe we are very aggressive with it," Sullivan said. "Every day there is somebody out there that is looking to harm those people that we protect, and you're right it could be a lone gunman it could be an organized group and we have to look at every single one of those possibilities."

Click Here for the Blotter Homepage.