Gerald Ford, the oldest living former U.S. president, was in a Rancho Mirage, California hospital Thursday undergoing medical tests, his office said. Ford, who is 93, was doing well at Eisenhower Medical Center, spokeswoman Penny Circle said in a statement. She did not disclose the nature of the tests. The former president has been hospitalized repeatedly this year, notably for a heart procedure in August. Ford, a Michigan Republican, was House of Representatives minority leader when President Richard Nixon chose him to replace Spiro Agnew, who resigned as vice president in 1973. Ford became president in August 1974 when Nixon resigned amid the Watergate scandal.