Correction: A previous version of this article incorrectly implied that an assassination attempt on Alabama Gov. George Wallace occurred in 1976. It occurred in 1972. The article also incorrectly stated that Gerald R. Ford was vice president in 1976. He was president.

GOP Presidential candidate Mitt Romney holds his Florida primary victory party in Tampa on Tuesday. (Linda Davidson/THE WASHINGTON POST)

The protection is not a reaction to any specific threats, one official said, but because of the growing crowds Romney is drawing on the campaign trail.

The Romney campaign recently requested the protection from the Secret Service and the Department of Homeland Security, the law enforcement official said. Federal law permits major-party presidential candidates that meet certain fundraising and polling thresholds to make a request for Secret Service protection. The request is then considered by the secretary of homeland security in consultation with congressional leaders.

Homeland Security Secretary Janet Napolitano and congressional leaders have approved Romney’s request, the law enforcement official said.

The officials, speaking on condition of anonymity to discuss sensitive security matters, confirmed the first report late Tuesday night by ABC News.

Romney campaign spokeswoman Andrea Saul declined to comment on the matter.

Romney is the second Republican presidential candidate to receive Secret Service protection this cycle. Businessman Herman Cain began receiving protection last fall until he dropped out of the race in December.

In anticipation of another busy campaign cycle, the Secret Service has requested $113.4 million to protect the eventual 2012 Republican nominee — a $4 million increase from the 2008 campaign and about two-thirds more than was spent for security during the 2004 election. Security for President Obama and Vice President Biden will be paid for out of a separate account.

Secret Service Director Mark Sullivan told House lawmakers in September that 2012 will be “a very demanding and challenging year” for his agency. In addition to protection for Obama, Biden and their families, the agency must provide protection for four former presidents and for visiting foreign dignitaries, and will serve as the lead law enforcement agency at a host of major events, including the Democratic and Republican presidential conventions.

The earliest a presidential candidate received Secret Service protection was eight months before the first primary contest in May 2007, when agents began tailing then-Sen. Barack Obama. Hillary Rodham Clinton (D) also had protection throughout her campaign because she was a former first lady.

Campaign trail security dates back to 1968, when Congress authorized protection of major presidential candidates after the assassination of Robert F. Kennedy (D) in California, according to the government official, who provided the following information on behalf of the Secret Service but wasn’t authorized to speak publicly on the issue.

By law, major-party presidential nominees and their running mates receive Secret Service protection during the general election, but candidates may seek protection earlier in the cycle if they meet a series of polling and fundraising thresholds.

The 2008 campaign proved particularly daunting for the Secret Service. The agency screened more than 4 million people at campaign rallies across the country. The decision to protect Obama so early in the cycle prompted the agency to divert personnel from other responsibilities and to use U.S. Customs and Border Protection and Transportation Security Administration officers to help screen bags and people at large events.

In addition to Obama and Clinton, John McCain (R), Biden and Sarah Palin (R) also received protection in 2008.

Despite the unprecedented attention paid to the 2008 campaign, it paled in comparison to the 1976 cycle, when the Secret Service protected 15 candidates and President Gerald R. Ford in response to the 1972 assassination attempt on Alabama Gov. George Wallace (R). Six candidates began receiving protection in 1975.

During the 1980 campaign cycle, Sen. Edward M. Kennedy(D) began receiving protection in Oct. 1979. In later years, several other ultimately unsuccessful but well-known candidates requested and received protection. The Secret Service provided protection during Jesse Jackson Jr.’s (D) 1984 and 1988 campaigns beginning in November 1983 and November 198. Pat Robertson(R) also had protection beginning in December 1987, while John F. Kerry (D) and John Edwards (D) had protection as they fought for the 2004 Democratic nomination.

Obama holds the record for receiving protection the earliest and had Secret Service agents at his side over the course of 629 days on the campaign trail. But Ronald Reagan (R) holds the record for the most “protection days:” Over the course of his 1968, 1976 and 1980 campaigns, the Secret Service protected Reagan for 791 days.

O’Keefe reported from Washington.