Barbara Bush, 91, entered Houston Methodist Hospital Wednesday morning as a precaution after suffering fatigue and coughing. She had not been feeling well for a couple of weeks but is resting comfortably, McGrath said Wednesday.
McGrath said the former first lady reported feeling "1,000 percent better" this morning.
"Antibiotics and some good rest seem to have restored her to better health," McGrath said in a statement today.
It's unclear when she will be released from the hospital.
The 92-year-old former president underwent a procedure “to protect and clear his airway that required sedation,” the statement said. George H.W. Bush remained in the ICU in stable condition today, according to the family spokesman.
"His medical team is actively evaluating him for extubation, and we are hopeful he will be discharged from the ICU in a few days," McGrath said in a statement today.
Doctors initially believed the 41st president would be allowed to return home later this week after several days of treatment, but his stay was extended. An earlier statement from the family spokesman had said there was no timetable for his release.
During his final presidential news conference Wednesday afternoon, President Obama said he had been in touch with the family about the Bushes' conditions.
"They have not only dedicated their lives to this country. They have been a constant source of friendship and support and good counsel for Michelle and me over the years," Obama told reporters. "They are as fine a couple as we know, and so we want to send our prayers and our love to them. Really good people."
ABC News' Karma Allen, Phillip Mena, Arlette Saenz, Veronica Stracqualursi and Gina Sunseri contributed to this report.