Guess again, because "Big B for President" doesn't stand for Biden, Babbitt or Bush. Just in case that button pops up on somebody's lapel, political insiders should know that it's part of a boomlet for Big Bill Bennett, the secretary of education, sparked by a fellow alumnus from Gonzaga High School here.

Dr. John Adams, who was at Gonzaga about the same time as Bennett, last week mailed out some of the buttons along with a cover letter explaining that the secretary's stand on drugs and AIDS were his "strength" and that he had met with Bennett "to urge him to run for president." He also wrote that he was forming a fund-raising committee.

Yesterday Bennett's office quickly disclaimed any knowledge of fund-raising efforts but did confirm that the secretary and Adams had met over lunch recently.

"Every year Gonzaga has a fund-raising auction, and since Bennett became secretary of education {February 1985} one of the auction items has been a lunch with the secretary. Dr. Adams has outbid everybody else so he could have the lunch," said Loye Miller, spokesman for Bennett.

Bennett turned down a similar appeal by Sen. Gordon Humphrey, who urged the secretary to test the waters in New Hampshire. But Bennett, wary that a campaign would only make it more difficult for him to get things done in his current job, in effect said "thanks but no thanks."

Or, as Miller quoted Bennett as saying: " 'I don't think it's in the cards this time.' "

Walter Cronkite, who lighted up the sky for a generation of space junkies with his coverage of U.S. space shots, will be back in his favorite orbit Nov. 9, this time hosting a benefit to build a national center for space education.

About $1 million already has been raised for the multimillion-dollar Challenger Center for Space Science Education, to be built somewhere in the Washington area as a memorial to the seven Challenger astronauts who died when their shuttle exploded shortly after liftoff in 1986.

All seven of the Challenger families are expected to attend the November event, a $250-a-plate dinner at the Pension Building.Cohosts will be Vice President George Bush and House Speaker Jim Wright. The honorary committee includes such names as Henry Kissinger, Margaret Truman Daniel, Caroline Kennedy Schlossberg, Edwin E. (Buzz) Aldrin Jr., Chuck Yeager, Tom Wolfe, Jack Lemmon, Prince Bandar and Lynda Carter.

On tap that evening will be the unveiling of a new release by MCA Records titled "The Mission Continues," featuring such artists as Stevie Wonder and Patti LaBelle. On stage will be John Denver, Lee Greenwood and possibly even Barbra Streisand, whose office is considering the engagement, according to James Rosebush, acting president of the proposed center.

Nancy Reagan goes off to summer camp in Maine Thursday for the day. In what has become an annual back-to-nature outing, Mrs. Reagan will visit 250 inner-city kids at Agassiz Village on the banks of Thompson Lake at West Poland, Maine, near Auburn-Lewiston.

An avowed former camper herself, the first lady will tour the camp, have lunch with the kids in what's billed as the largest log cabin in the United States and will definitely go near the water to watch campers in their various activities.

However, Mrs. Reagan's press secretary, Elaine Crispen confirmed yesterday that the first lady is not expected to take along her bathing suit, which pretty much rules out a water ballet, one of the few dances she has not tried in public appearances during her husband's administration.

Nobody's invited her, but even if somebody did, Nancy Reagan would just say no, the White House said yesterday when asked if she'd be at a Sept. 19 anti-drug-abuse fund-raising event in Edmonton, Alberta.

"September is pretty well committed," said press secretary Elaine Crispen of the first lady's schedule, which includes a White House dinner for the prime minister of Sweden, Ingvar Carlsson, a date with Pope John Paul II in Los Angeles, a congressional picnic and a private dinner for the king and queen of Spain.

Organizers of the Edmonton event, supposedly part of a Canada-wide effort called "Disons Non Canada/Just Say No," dropped off literature at the White House last week. Despite published reports in Canada that Mrs. Reagan's acceptance will determine whether the fundraiser is held, the group left no invitation, the White House said.

Promoter Shiloh Quinn, calling from Canada, said that's because the group was waiting for Mila Mulroney, Canada's first lady, to extend the invitation in the next few days.

Told that the White House had said Mrs. Reagan's September schedule is full, Quinn said, "Well, then, if she said October or November, that would be fine with us. Just give us an available date."

Paul Laxalt takes his presidential campaign today to the Neshoba County (Miss.) Fair, the same place Ronald Reagan headed after he won the nomination at the 1980 GOP convention. Awaiting Laxalt at the fair will be the same thing that awaited Reagan -- a rocking chair handcrafted by Greg Harkin of Jackson, Miss.

The former Nevada senator, who will be 65 on Aug. 2, is expected to take the chair to his High Knob, Va., country home, which, of course, is just a whoop and a holler from the White House, should he need to move it again.

If Reagan ever took his rocker to the White House, nobody has ever seen him use it, a spokesman for the president said yesterday.

"Let me win," goes the prayer, "but if I cannot win, let me be brave in the attempt."

This year, about 4,500 Special Olympians from 70 countries will be bravely attempting to win at the seventh International Summer Special Olympics Games in South Bend, Ind., Sunday through Aug. 8.

In addition to such celebrities as Mary Lou Retton, Arnold Schwarzenegger, Bart Conner and Jane Fonda, there to cheer on the contestants will be the wives of nine foreign leaders, including Illinois-born Margaret Chant Papandreou of Greece, Pennsylvania-born Carolina Isakson de Barco of Colombia and District of Columbia-born Queen Noor (formerly Lisa Halaby) of Jordan.

Deputy Secretary of State John Whitehead will host a dinner at the State Department Friday night for the foreign visitors and the Special Olympics board, whose chairman is Eunice Kennedy Shriver and president is Sargent Shriver.

Founded by Eunice Shriver in 1968, the games are the culmination of the world's largest program of year-round sports training and athletic competition for the mentally retarded.

Appropriately and in salute to the original Olympic Games, Greece's Papandreou will lead her delegation into the University of Notre Dame stadium on Sunday to officially open the competition of more than 100 events in 14 sports.