Former US President George HW Bush and his wife Barbara Bush remain in hospital in Houston, Texas, according to a spokesman.
The 41st president, who was admitted with pneumonia on Saturday, is still in the intensive care unit, relying on a ventilator to breathe.
The 92-year-old had a breathing tube inserted on Wednesday in a procedure to clear his airway.
Wife, Barbara, who has had bronchitis, said she was feeling "1,000% better".
Mrs Bush, 91, was admitted on Wednesday suffering from fatigue and a cough.
"President Bush had a good night's rest," spokesman Jim McGrath said on Thursday.
"We are hopeful he will be discharged from the ICU in a few days."
He said the couple had received "an uplifting visit" from longtime friend former Secretary of State James Baker, who lives in Houston.
President-elect Donald Trump, President Barack Obama and former President Bill Clinton have sent their well wishes via Twitter.
In a letter addressed 10 January, Mr Bush - the oldest living US president - wrote to Mr Trump to excuse himself from attending his inauguration as 45th US president on Friday.
Mr Bush wrote that "my doctor says if I sit outside in January, it will likely put me six feet under".
"Same for Barbara. So I guess we're stuck in Texas," he wrote, adding that they will be "with you and the country in spirit".
Mr Bush, who served as US president from 1989-93, spent a week in hospital in the US state of Maine in 2015 after falling and breaking a neck bone.
He also suffers from a form of Parkinson's disease and uses a wheelchair.
Mr Bush's son, George W Bush, was elected president in 2000 and served two terms as the nation's 43rd president.
The elder Bush was born 12 June 1924, in Massachusetts and also served as a congressman, CIA director and vice-president to Ronald Reagan.