Civil rights icon and Georgia congressman Rep. John Lewis has been hospitalized but is expected to be released Sunday, his spokeswoman says.
Spokeswoman Brenda Jones told CNN that Lewis is under routine observation but she did not give details of the nature of his illness or where he is hospitalized.
CNN affiliate WSB-TV reported that Lewis was being treated at a hospital in metro Atlanta, and the station quoted unnamed sources as saying Lewis became ill on a flight to Atlanta on Saturday.
"Rep. Lewis remains in the hospital today until doctor's observations are completed. He is resting very comfortably and fully expects to be released very soon. He is grateful for the concerns and well wishes of Georgians, colleagues, family and friends," Jones said in a statement.
Lewis, 78, has represented Georgia's 5th Congressional District, which includes much of the city of Atlanta, since first being elected in 1986.
In February 2011, President Barack Obama presented Lewis with the Presidential Medal of Freedom, the country's highest civilian honor.
The long-serving Democrat was a young activist and leader of the Student Nonviolent Coordinating Committee when, in March 1965, he joined forces with Martin Luther King Jr. to lead a voting rights march out out Selma, Alabama.
But as the nonviolent demonstrators approached the Edmund Pettus Bridge, on their way to the state capital in Montgomery, they were confronted by heavily armed state troopers and local police. When the march refused to turn back, protesters were set upon and beaten.
The images from "Bloody Sunday" -- and Lewis, who was photographed under assault and suffered a fractured skull -- helped galvanize support for the Voting Rights Act, which was signed into law by President Lyndon B. Johnson months later.