Updated at 7:08 p.m. ET: Former President George H.W. Bush was battling an elevated fever Wednesday and was in "guarded condition" in a hospital intensive care unit, a family spokesman said.

 "The President is alert and conversing with medical staff, and is surrounded by family," said a statement from family spokesman Jim McGrath. Bush, 88, was moved to the intensive care unit at The Methodist Hospital at the Texas Medical Center in Houston on Sunday, McGrath said. 

Bush has been in the hospital since Nov. 29 for treatment of complications related to bronchitis. After initial expectations that he would be hospitalized for only a few days proved to be wrong, doctors said through a hospital statement on Dec. 13 that they expected Bush would "be able to celebrate Christmas at home."

But the 41st president remained at The Methodist Hospital -- where he was visited on Christmas by his wife, Barbara, his son, Neil, Neil's wife, and his grandson, Pierce -- all of whom brought him a meal of Chinese food for Christmas dinner, The Houston Chronicle reported.

He also received gifts, emails, and telephone calls from family members and close friends, NBC's Janet Shamlian reported.

On Wednesday, McGrath told NBC News that the former president's fever was elevated from the previous day, although he said that he did not know by how much. Earlier, McCrath had said that doctors saw a "slight improvement" in Bush's condition that morning.

McGrath said that Dorothy Bush, his daughter, visited Wednesday, and George W. Bush, the 43rd president, would be visiting soon.

Bronchitis is a common condition in which the bronchial tubes in the lungs become inflamed and produce mucus, which creates the need to cough, according to the Centers for Disease Control and Prevention. It can turn serious in people with weak immune systems, including children and the elderly. Symptoms such as chest pain, weakness and coughing typically last two weeks, but can linger for as long as two months. 

In the weeks since he was admitted, Bush has had a low-grade fever, but doctors have said they are "cautiously optimistic" he will recover, Shamlian reported.

George Kovacik, a hospital spokesman, said in a statement earlier this week that Bush was in stable condition. 

“His doctors feel he should build up his energy before going home. They remain optimistic about his full recovery and are being extra cautious with his care,” the statement said.

Slideshow: The life and times of George H.W. Bush

Robert Sullivan / AFP - Getty Images

Leader of an American political dynasty, George Bush's influence was felt beyond his terms as president and vice president. Take a look back at his life and career.

Launch slideshow

Bush was elected president of the United States in 1988, the capstone of a long career of public service.

He was a Texas Republican member of the House of Representatives in the 1960s and 1970s and head of the CIA in 1976-1977. The organization’s headquarters in Langley, Va., was later renamed the “George Bush Center for Intelligence.”

Bush lost his first bid for the Republican nomination for the U.S. presidency in 1980, at which time Ronald Reagan chose him to be his running mate. He went on to serve two terms as Reagan’s vice president before winning the presidency. He was defeated for re-election in 1992 by Bill Clinton.

In late 2004, Bush teamed up with Clinton to raise money for the victims of the Asian tsunami. That effort was so successful, the two former presidents did the same for Katrina victims in 2005. 

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