George HW Bush has been admitted to a hospital in Houston Texas after suffering breathing difficulties.
The former US President "will be held for observation... as a precaution", according to his spokesman James McGrath.
At 90 years of age, old George Bush senior is the oldest living former President. He succeeded Ronald Reagan as President, beating Democratic opponent Michael Dukakis in 1989.
A veteran of World War Two, Bush can now no longer make use of his legs and was recently afflicted by a bronchitis related cough.
White House spokesperson Eric Schultz released a statement Tuesday night:
The President has been made aware that President Bush was admitted to the hospital. President Obama and the First Lady send their good wishes to the former President and the entire Bush family during this holiday season.
Bush's son George W Bush was President from 2001 to 2009, beating Al Gore and Jon Kerry. His other son, former Florida governor Jeb Bush, recently announced he would "actively explore the possibility of running for President of the United States".
Most Republican operatives had assumed Bush would not run for the nomination given his lack of campaigning activity and fundraising.