Images promoting the comparison have been removed from the site. The Sacramento Bee reported that the Web site showed Obama in a turban next to bin Laden, the al Qaeda leader, and said: "The difference between Osama and Obama is just a little B.S."
County Republican Chairman Craig McGlashan did not immediately respond to a telephone message left at his law office by The Associated Press on Wednesday.
The images have been removed from the site.
A spokesman for the state Republican Party, Hector Barajas, said the party asked Sacramento GOP officials on Tuesday to remove the material.
Meanwhile, the Secret Service is looking into a second allegation that a participant at a Republican political rally shouted "kill him," referring to Obama.
The Scranton Times-Tribune reported that someone in the crowd shouted "kill him" after the mention of Obama's name during a rally Tuesday for Republican vice presidential nomineein Scranton, Pennsylvania.
Last week The Washington Post reported a similar incident during a Palin rally in Clearwater, Florida. The Secret Service investigated that allegation and found no indication that "kill him" was ever said, or if it had been said, that the remark had been directed at Obama.
Listening to tapes of that rally, the Secret Service heard "tell him" or "tell them," but agents never heard "kill him," Secret Service spokesman Eric Zahren told The Associated Press on Wednesday.
The Secret Service is a government agency principally charged with protecting the safety of the president, vice president and selected other dignitaries. The Service's agents are guarding Obama, the Democratic presidential candidate;, his Republican Rival; and their vice presidential running mates, Palin for McCain and Sen. Joe Biden for Obama.
In both the Clearwater and the Scranton instances, the Service learned of the alleged threats only through media reports.
"We would ask that anyone overhearing threatening language bring it to the attention of the Secret Service or other law enforcement at the event immediately," Zahren said.
The Secret Service cannot prevent or police bad taste or poor behavior at public events, Zahren said, but the agency draws the line at threatening language.
"We do not have the luxury of discounting such language as simply bad taste or bad behavior without further investigation," he said.
So far, the Secret Service has not found anyone who heard "kill him" Tuesday except for the Times-Tribune reporter.
Shouts of "traitor," "terrorist," "treason," "liar" and even "off with his head" have rung from the crowd at Republican rallies.
The anti-Obama taunts and jeers are noticeably louder when McCain appears with Palin, a big draw for Republican social conservatives. She accused Obama last week of "palling around with terrorists" because of his past, loose association with a 1960s radical.