Story highlights Both Bushes remain in a Houston hospital but are improving

Barbara Bush was admitted for treatment of bronchitis to the same hospital on Wednesday

Washington (CNN) Former First Lady Barbara Bush could be released from the hospital as soon as Sunday, a spokesman for her husband, former President George H.W. Bush, said Saturday.

Both Bushes remain in a Houston hospital but are improving, Jim McGrath said.

"Following another good night's rest, President and Mrs. Bush have both continued to improve over the past 24 hours. Mrs. Bush could possibly be discharged from Houston Methodist Hospital tomorrow, while President Bush will be remaining in the ICU for observation for a few more days," McGrath said in a statement. "President Bush is breathing well without any mechanical assistance, his spirits are high, and he is looking forward to getting back to a regular schedule. In fact, he called his office last night at 6:30 p.m. to check in on his staff."

The former president, 92, was admitted to the hospital on January 14 due to a respiratory issue stemming from pneumonia. Barbara Bush was admitted for treatment of bronchitis to the same hospital on Wednesday.