Jullie Ward, a spokeswoman for Avera McKennan Hospital in Sioux Falls, said the 89-year-old former senator from South Dakota was admitted to the Sioux Falls hospital for fatigue after completing a lecture tour. She said doctors expect him to make a full recovery and be released in a couple of days.
Ward said the family has asked for privacy while McGovern recovers and rests.
McGovern, a South Dakota congressman from 1957 to 1961 and U.S. senator from 1963 to 1981, ran for president against incumbent Richard Nixon in 1972 and lost in a historic landslide.
McGovern had moved to St. Augustine, Fla., in 2008 after the death of his wife, Eleanor. His latest book, "What it Means to Be a Democrat," is scheduled to be released Nov. 10. He was scheduled to be in his hometown of Mitchell, S.D., four days after its release for the 2011 McGovern Conference.
McGovern was elected to his first of three Senate terms in 1962. He ran for president three times, making a try for the nomination in 1968 and 1984 in addition to the 1972 race.
Despite the Watergate break-in that year, Nixon won a second term in one of the biggest landslides in modern history. The liberal McGovern won only one state, Massachusetts.
Much of McGovern's recent work has focused on world hunger.
He and former U.S. Sen. Bob Dole, a Republican, were honored in 2008 with the World Food Prize, a distinction that some observers have called the Nobel Prize for hunger.
Their George McGovern-Robert Dole International Food for Education and Nutrition Program, established in 2000 and funded primarily through Congress, provides millions of meals to children in the U.S. and some three dozen countries across the world.
McGovern has remained active in recent years, even skydiving in Florida to celebrate his 88th birthday.