FORMER U.S. President Bill Clinton will remain overnight in a Southern California hospital following a urological infection, but he has continued to make "excellent progress" and is expected to be discharged on Sunday, his spokesman said in a statement on Saturday.

The 75-year-old, who served as president from 1993 to 2001, entered the University of California Irvine Medical Center on Tuesday evening after suffering from fatigue.

Clinton spokesperson Angel Urena said the former president was doing well.

"He is in great spirits and has been spending time with family, catching up with friends, and watching college football," Urena said in a statement posted on Twitter.

Clinton's wife, former Secretary of State and 2016 Democratic presidential nominee Hillary Clinton, was at the hospital on Saturday.

Since his admission to the hospital's intensive care unit, he has received fluids and antibiotics, his doctors said.

Clinton, who was in California to attend a dinner and reception for his foundation in Los Angeles County, has dealt with health problems in the past. He had quadruple bypass operation in 2004 and a procedure to open a blocked artery in 2010.

The Democrat served two four-year terms in the White House, overseeing strong economic growth while engaging in bruising political battles with congressional Republicans.

The Republican-controlled House of Representatives impeached him in 1998 on charges arising from his sexual relationship with White House intern Monica Lewinsky, but Clinton was acquitted by the Senate.

He was only the second U.S. president to be impeached. Republican President Donald Trump would later become the third when he was impeached twice during his term.

Clinton, a former Arkansas governor, has combined a folksy charm with deep knowledge of policy issues. He defeated an incumbent president, Republican George H.W. Bush, in 1992 and then beat longtime Republican Senator Bob Dole to win re-election in 1996.