Previously, Romney's campaign had paid two or three former Secret Service agents to provide security at his events, according to The Associated Press. But as the 2012 race has heated up and more and more people have begun to attend Romney's events, it has become increasingly difficult for his team to ensure security.
Romney is the only current Republican candidate receiving Secret Service protection, although officials said the other candidates might qualify if they requested it. Herman Cain requested and received Secret Service protection in November, but he dropped out of the presidential race shortly thereafter.
The presidential nominee from each major party is automatically offered Secret Service protection, but candidates can request protection earlier if they meet certain criteria and are approved by the Department of Homeland Security and a congressional advisory committee.
The Secret Service does not comment on the specific reasons for granting a candidate early protection, but typically, there has to be a credible threat to the candidate's safety. Several prominent or controversial candidates, including Jesse Jackson, Edward Kennedy, Pat Robertson and Barack Obama, received early Secret Service protection in past elections.
Romney is the 13th presidential candidate known to have received early protection.