Tom Lantos, the only Holocaust survivor to serve in the U.S. Congress and a passionate advocate for human rights during 27 years in office, has died. He was 80.

Lantos said in January that he had cancer of the esophagus and would resign at year's end rather than seek a 15th two-year term representing California's 12th District. Lynne Weil, a spokeswoman for Lantos, said he died Monday morning at Bethesda Naval Medical Center in Maryland of complications from cancer.

Lantos in 1983 co-founded the Human Rights Caucus, a bipartisan group of lawmakers that uses briefings and visits by world leaders to speak out for victims of political, religious, ethnic and racial persecution around the globe. He also was a leading advocate for Israel.

"He was a great champion of religious liberty," said Bob King, the Democrat congressman's chief of staff for more than two decades.

While he was extremely proud of his Jewish heritage, Lantos also had strong ties to The Church of Jesus Christ of Latter-day Saints, King said.

His wife, whom he married in 1950, was a member of the LDS Church. The couple had helped the LDS Church host various events in Washington, D.C., over the years, such as the Christmas lighting ceremonies at the temple there.

When Brigham Young University, looking to establish a center in Jerusalem, met resistance from Orthodox Jews, Lantos was "very quick and very early" to put his name on a letter to Israeli leaders.

"It gave the letter great credibility with other members of Congress — if a Holocaust survivor can sign it, anybody can," King said. "And it gave it great credibility in Israel."

In 2001, Lantos spoke at BYU's commencement ceremony. Alongside LDS apostle Elder Joseph B. Wirthlin, Lantos was awarded an honorary doctorate from the university.

If the juxtaposition seems odd — a Holocaust survivor and liberal California politician making good in Utah — that was just Lantos, King said.

"He disagreed with Newt Gingrich on most issues, but they were great friends," he said. "They stayed up into the late hours discussing Hungarian history. Then they went out and voted against each other."

President Bush said in a statement that Lantos "was a living reminder that we must never turn a blind eye to the suffering of the innocent at the hands of evil men." Flags at the White House were lowered to half-staff in his honor.