A little more than seven months from now, Ronald Reagan will leave behind the pomp and power of the White House and become just an ordinary American citizen.

Well, sort of.He won't have Air Force One or his Marine helicopter, but that doesn't mean he will have to drive himself up the dirt road to his California ranch - or any place else for that matter.

"He will get government protection 24 hours a day, similar to what we do now," Jane Vezeris, spokeswoman for the Secret Service, said.

Vezeris won't go into detail about what this means, but Secret Service protection routinely includes chauffeurs to drive the protected person safely from place to place.

Ex-presidents also receive pensions, which amounted to $94,838 each last year for Nixon, Ford and Carter. They get funds for office expenses, which, according to the General Accounting Office, totaled approximately $1.3 million in 1987.

It was not always so. Harry Truman opened his own mail, bought his own stamps and drove his own car after he returned to Independence, Mo. Congress began covering such expenses with the Former Presidents Act in 1958.

Lifetime Secret Service protection was extended to former presidents and their wives in 1965, after President Kennedy was assassinated, although Theodore Roosevelt is the only former president in history to be attacked, and that was when he was running for president again.

Last year, the protection cost about $9.3 million, and some in Congress are questioning whether it is worth it.

Sen. Lawton Chiles, D-Fla., has introduced legislation cutting off automatic Secret Service protection for former presidents five years after they leave office. If a former president died within the five years, protection for his widow would continue for one year.

"Former presidents are visible figures," said Chiles. "Some of the excesses, like the large number of Secret Service men that travel with them, do not sit well with the American public. Such symbols connote inappropriate trappings of office."

Richard Nixon voluntarily gave up his Secret Service protection in 1985 and now pays his own bodyguards. His assistant, John Taylor, told Chiles that Nixon has sat in the grandstand at baseball games and eaten in fast-food restaurants without any untoward incidents.

Ford, who continues to use his Secret Service agents, endorsed Chiles' bill also.

Jimmy Carter, however, told the senator, "The elimination of security would make it almost impossible for us to live a normal private life at home free of uninvited visitors, to attend major events if our attendance is publicized, or to travel to many places in our country or abroad."