Lantos, who chaired the House Foreign Affairs Committee, announced on Jan. 2 that he would leave Congress at the end of his 14th term due to his diagnosis.

In a release announcing his retirement in January, Lantos said, “It is only in the United States that a penniless survivor of the Holocaust and a fighter in the anti-Nazi underground could have received an education, raised a family, and had the privilege of serving the last three decades of his life as a Member of Congress.”

Lantos had distinguished himself as a human rights activist since his election in 1980, and founded the Congressional Human Rights Caucus in 1984.

Born in Hungary, Lantos often was the first lawmaker to visit countries long vacated by United States officials. In 2004, he was among a small group of lawmakers to visit Libya, the first visit to that country by members of Congress since the 1960s, according to the Almanac of American Politics. In recent years he worked tirelessly to secure funding for people displaced by the fighting in Sudan.

Democrats have carried the seat since Lantos defeated the Republican incumbent nearly 28 years ago. Sen. John Kerry (D-Mass.) received 72 percent of the vote in the district in 2004.

In 2006, Lantos received 76 percent of the vote, but he anticipated a challenge from the left in 2008 from former California state Sen. Jackie Speier.

Rep. Howard Berman (D-Calif.) would be in line to succeed Lantos on Foreign Affairs.

Lantos spoke frequently of his childhood sweetheart Annette, who also lived through the Holocaust. The two married and Annette worked with Tom Lantos as a volunteer for the Congressional Human Right Caucus.

Lantos is survived by Annette, his daughters Annette and Katrina, 17 grandchildren and two great-grandchildren.