A fever that has kept former President George HW Bush in a Houston hospital over Christmas has worsened, and doctors have put him on a liquid-only diet, an official said.
Jim McGrath had earlier said the fever had gone away but he later corrected himself and said the fever had "elevated" in recent days.
He said doctors have also put the 88-year-old former president on a liquid diet, though he could not say why.
Mr McGrath said doctors have been treating the "stubborn" fever with Tylenol but still have not discovered a cause.
He said the bronchitis-like cough that initially brought Mr Bush to the hospital on November 23 has improved.