Herman Cain became the first Republican presidential candidate to receive Secret Service protection. There have been threats against Cain, although the nature of the threats is unclear.
Cain asked for the security and Homeland Security Secretary Janet Napolitano and congressional leaders approved his request Thursday, Secret Service spokesman Ed Donovan confirmed.
There have been threats against Cain, who had been experiencing a bounce in the polls, according to an official with knowledge of the situation who asked not to be identified because of the sensitive nature of the situation. The nature of the threats was unclear.
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Donovan would not say whether there had been any threats or discuss why protection was being provided.
The campaign confirmed in an email early Friday that Cain was receiving federal protection.
"Due to the recent surge in the polls and the large crowds of enthusiastic supporters at recent campaign events, we are appreciative of the extra level of protection provided by these elite professionals," the Cain campaign said in a statement.
While it's unknown whether a specific incident triggered the request, police reports show that Cain's campaign has been the target of a threatening phone call on at least one occasion.
On June 1, Cain's campaign office in Stockbridge, Ga., reported receiving a call from someone who did not identify himself but who claimed to be a member of the Ku Klux Klan. The man said that Cain, who is black, should not run for the White House.