Most presidential candidates are entitled to receive Secret Service protection from the federal law enforcement agency that also provides security to all U.S. presidents and vice presidents and their families. Serious presidential candidates begin receiving Secret Service protection during the primary campaigns and continue to get coverage through the fall election if they become the nominee. Secret service protection for presidential candidates is provided for in federal law.

Here are answers to some of the most commonly asked questions about Secret Service protection for candidates.

The Secret Service protects only “major” presidential candidates and only those who request coverage. The secretary of Homeland Security determines which presidential candidates are considered major after consultation with an advisory committee, according to the agency. Major presidential candidates can decline Secret Service Protection.

The Homeland Security director makes his determination on which candidates get Secret Service protection in consultation with an advisory panel that includes the speaker of the U.S. House of Representatives; the House minority whip; the Senate majority and minority leaders; and an additional member chosen by the committee itself.

Major candidates are those that have considerable prominence among the public and have raised substantial money for their presidential campaigns.

Specifically, primary candidates become eligible for Secret Service protection, according to the Congressional Research Service, if they:

• Are publicly declared candidates.
• Are actively campaigning nationally and are contesting at least 10 state primaries.
• Are pursuing the nomination of a qualified party, one whose presidential candidate received at least 10 percent of the popular vote in the prior election.
• Are qualified for public matching funds of at least $100,000, and have raised at least $10 million in additional contributions.
• Have received by April 1 of the election year an average of 5 percent in individual candidate preferences in the most recent national opinion polls by ABC, CBS, NBC, and CNN, or have received at least 10 percent of the votes cast for all candidates in two same-day or consecutive primaries or caucuses.

Presidential and vice presidential nominees and their spouses are to receive Secret Service protection within 120 days of a general presidential election. In modern history, however, major candidates receive Secret Service protection well before that time, usually early in the primary campaigns in the late winter and early spring.

Not every presidential candidate wants Secret Service protection, though. Ron Paul, 2012 Republican presidential hopeful popular among libertarians, declined Secret Service protection. The Texas congressman described Secret Service protection as a form of welfare. “You know, you’re having the taxpayers pay to take care of somebody. I’m an ordinary citizen. I would think I should pay for my own protection. And it costs, I think, more than $50,000 a day to protect those individuals. That’s a lot of money,” Paul said.

The cost of providing Secret Service protection to presidential candidates exceeds $200 million. The costs have risen dramatically as the field of candidates has grown larger. The cost of providing Secret Service protection for candidates in the 2000 election was about $54 million. It rose to $74 million in 2004, $112 million in 2008, $125 million in 2012 and about $204 million in 2016.

Secret Service protection costs taxpayers about $38,000 a day per candidate, according to published reports.

Congress passed a law authorizing Secret Service protection for presidential candidates for the first time following the 1968 assassination of U.S. Sen. Robert Kennedy, who was seeking the Democratic presidential nomination.