Former US president George HW has been admitted to hospital suffering from low blood pressure and fatigue.
Spokesman Jim McGrath tweeted just after 2pm on Sunday that Mr Bush, 93, is likely to remain in the hospital for a few days.
Mr Bush, who served as president between 1989 and 1993, is being treated at Southern Maine Health Care in Biddeford, Maine.
Mr McGrath said he is "awake, alert and not in any discomfort".
The 41st president is spending the summer at the family compound in Kennebunkport.
He attended a pancake breakfast on Saturday at the local American Legion.
Mr Bush's wife of 73 years, Barbara, died last month. The day after her funeral, Mr Bush was taken to hospital in Houston for 13 days with an infection.