Clinton is attending the Oct. 29 launch of the space shuttle Discovery "to recognize Sen. Glenn's historic return to space and to recognize the importance of our nation's space program and the hard work of the men and women that make that program possible," White House Press Secretary Joe Lockhart said Tuesday.
NASA says the last sitting president to watch a manned space launch at the Kennedy Space Center was in November 1969, when Richard Nixon was present for the launch of Apollo 12.
Glenn, 77, who made his first space flight in 1962, will be the oldest person to ride a rocket as he makes himself a human guinea pig for medical studies testing the effects of weightlessness on seniors.
Lockhart characterized the president's attendance at the liftoff as a celebration of "this great achievement both for NASA and for Senator Glenn."
On Oct. 30, Clinton will shuttle to New York for another campaign appearance on behalf of Rep. Charles Schumer, who is battling to unseat New York's GOP Sen. Alfonse D'Amato.