Former President George H. W. Bush’s doctors on Sunday said he would need to “build up his energy” before he can be released from a Houston hospital.

In an email statement, Methodist Hospital spokesman George Kovacik said doctors were being cautious, but expected the 41st president to make a full recovery, according to the Associated Press.

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

Bush was admitted to the hospital in late November to receive treatment for bronchitis. Bush’s aides at the time said the illness was not life-threatening and expected that he would be home in time for Christmas.

Reports last week said that Bush’s condition had improved and that he was in a therapy program to help him recover his strength.