George Bush Sr has been moved into intensive care after suffering "a series of setbacks that include a persistent fever," according to a family spokesman.
Doctors are "cautiously optimistic" about the 88-year-old former president's health, he added.
Video report by Debi Edward.
More top news
A man who used a pickaxe and sledgehammer to ruin Donald Trump's Hollywood Walk of Fame star has avoided jail.
Wet, windy and turning wintry
A bull which escaped from an abattoir led police on a two hour wild goose chase through the streets of New York.