A spokeswoman with the FBI's Washington Field Office said the Secret Service intercepted a "suspicious letter" and the FBI was testing it for the highly toxic material, The Washington Post reported.
"U.S. Secret Service can confirm that the White House mail screening facility intercepted a letter addressed to the White House that [was] similar to letters previously addressed to Mayor Bloomberg in New York," the Secret Service said in a statement. "This letter has been turned over to the FBI Joint Terrorism Task Force for testing and investigation."
On Wednesday, authorities intercepted ricin-contaminated letters mailed to Bloomberg and the gun-control group he founded, Mayors Against Illegal Guns, which has been an outspoken advocate in the recent push for stricter gun laws.
Earlier this year, ricin-laced letters were sent to Obama, Sen. Roger Wicker, R-Miss., and a Mississippi judge. Police in Washington state last week also arrested a man in a death threat to a judge and two ricin-tainted letters sent earlier this month.