Former President George Herbert Walker Bush will spend Christmas in a Houston, Texas, hospital despite doctors’ hopes last week he could be home by the holiday, his spokesman told CNN.

Bush has had a few setbacks in the last week, including a low-grade fever, that have been frustrating to him and his doctors.

“But his doctors are cautiously optimistic” about a release in the not too distant future, spokesman Jim McGrath said.

Methodist Hospital spokesman George Kovacik said Sunday that Bush remained “in stable condition in the hospital” and that doctors so far have not been able to set a date for his release.

“His doctors feel he should build up his energy before going home. They remain optimistic about his full recovery and are being extra cautious with his care. No discharge date has been set at this time,” Kovacik said.

Bush, who is 88, originally had been fighting bronchitis and an associated cough but in the last few weeks had been undergoing some physical therapy to help prepare him to go home.

The former president has been in the hospital for just over a month. He was first hospitalized from November 7 through 19, then readmitted on November 23.

He is the oldest living former president and a World War II veteran.