Donnelly, a state assemblyman who is popular with the tea party, has repeatedly said this week that Neel Kashkari supported Shariah banking code when he was a senior official at the U.S. Treasury Department in 2008. On Facebook, Donnelly posted a link to a banking seminar hosted by the department during which Kashkari, a Hindu, delivered opening remarks.
"As far as I'm concerned, this type of stupidity disqualifies Tim Donnelly from being fit to hold any office, anywhere. Donnelly is no longer a viable option for California voters," Issa, who has endorsed Kashkari, said in a statement.
Aaron McLear, a spokesman for Kashkari, declined to comment on Donnelly's statements. He said the seminar at which Kashkari delivered remarks "was about how you can get capitalist free market principles into fundamentalist Islamic countries, not the opposite."
A Field Poll taken in April showed Donnelly with 17 percent support and Kashkari with 2 percent. Gov. Jerry Brown, a Democrat, is expected to easily win the top spot in the June 3 primary and advance to the November election.
Donnelly has continued to repeat the sentiments, even after apologizing during a live radio interview Wednesday for a Twitter message that accused Kashkari of "submission to" Shariah law, which has since been deleted.
Several posts on the topic remained live on Donnelly's Facebook page Thursday evening, including a link to the agenda for the 2008 event. Donnelly did not respond to a request for comment Thursday.
It is not the first time Donnelly has come under fire for topics related to race and ethnicity. He was elected to his conservative San Bernardino County district in 2010 after founding a branch of the Minuteman border patrol, which scours the U.S.-Mexico border in search of people attempting to enter the country illegally.
In March he posted a Twitter message comparing President Barack Obama's gun control policies with those of dictators such as Adolf Hitler, Joseph Stalin and North Korea's Kim Jong Il.
Earlier this week, he was the lone vote in the state Assembly against a bill that prohibits state government departments from selling or displaying items with an image of the Confederate flag. Donnelly's vote prompted the Assembly Republican caucus to respond with a statement saying the flag "is a symbol of racism, violence, and oppression for many in our state."
Harmeet Dhillon, vice chairwoman of the state GOP, said Donnelly should apologize for his "bigoted" rhetoric.
"It is clearly exploiting fear of Muslims in the electorate," she said. "Because Kashkari is from India, he has brown skin, he has a different name. I think the attack is clearly aimed at exploiting voters who hold those prejudices."
Issa said that as a Lebanese Christian, he faced similar unfounded allegations from an opponent when he ran for Congress.
"It is crap like this that gives Republicans a bad name and there is no place in the Republican Party or in this race for someone like Tim Donnelly," he said.
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