Republican National Committee communications director Sean Spicer and costume maker Jonn Schenz, after wearing the costume at a White House Easter Egg Roll during the Bush II administration.

The White House is expecting more than 35,000 people Monday on the South Lawn for the annual Easter egg roll — an event that began some 135 years ago and has evolved into a major Washington happening.

Presidents now regularly appear, but that apparently wasn’t always the case. Judging from photos, it doesn’t appear that President Lyndon Johnson attended, according to Margaret Harman of the Lyndon B. Johnson Library audiovisual archives. He preferred to spend Easter at the ranch in Texas.

A great part of the event — at least for the kids — is the appearance of the Easter Bunny, who became a regular at the event at least as far back as the Nixon administration — and perhaps earlier.

One of the first to don the bunny costume was Nixon advance man John E. Nidecker, who did the honors at least once during the Nixon administration, former Nixon aide Stephen Bull recalled.

(Nidecker, who died in 1988, is also said to be the inventor of the massive balloon drops at political conventions — starting with the 1964 GOP convention. And he sparked an investigation of South Korean influence-peddling in 1974 when he blew the whistle on an attempted $10,000 “gift” by a South Korean official at the end of a Nixon trip there.)

Over the years, a number of well-known administration officials have done the honors in the Mr. and Mrs. Bunny costumes.

Bush II White House counsel Fred Fielding wore the costume in 2008 and associate counsel Amy Dunathan was Mrs. Bunny. Ursula Meese, wife of Reagan aide and attorney general Edwin Meese, was Mrs. Bunny every year but one during the Reagan and Bush I administration, according the manufacturer, Jonn Schenz of Cincinnati, who makes the outfits and brings them gratis each year.

Laura Bush and President George Bush start the race at the Annual White House Easter Egg Roll on the South Lawn in 2008. (Kevin Clark/The Washington Post)

Keith Hennessey, former head of the Bush II National Economic Council who now teaches at Stanford Business School, did the honors a couple of times during the Bush II era, as did Republican National Committee communications chief Sean Spicer, who was then the assistant U.S. Trade Rep.

The Clinton administration didn’t use senior staff in the bunny costumes.

“We used cabinet-level people,” senior staff and famous folks “as readers to the kids,” said Melinda Bates, the White House Egg Lady for a record eight years as director of the visitors office.

In 2000, she recalled, “we had Robert De Niro on the lawn reading a story to the kids.” De Niro, who often plays some truly scary characters on screen — Taxi Driver, Goodfellas, and Cape Fear — was nonetheless a great hit, Bates said.

Wearing the costumes is no simple matter. In addition to getting hot — “It gets hotter than hell,” Schenz agreed — and uncomfortable, it’s very hard to see through the bunny’s mouth — though everyone looks at the bunny’s eyes when they talk to it. (The bunny, however, is not supposed to talk.)

The limited vision can even be dangerous, not so much for the bunny as for the little kids running underfoot, Spicer recalled. That’s why the bunnies have a handler to guide them as they wander about. Volunteers sign up for specific time slots — each an hour or so.

“Early morning is key,” Spicer advised, before the day — and the costume — heat up.

We repeatedly asked the White House last week and this for any info on the bunny customs during the Obama egg rolls but got no response. Maybe this info is considered classified?