Speaking in Moscow, Lantos called the 1974 Jackson-Vanik amendment a "relic of the Cold War" and vowed to "spare no effort" in seeking its removal.
Lantos is the chairman of the U.S. House Committee on Foreign Affairs.
The amendment links bilateral trade to emigration rights.
Russia has long urged the United States to cancel the amendment. Moscow regards the amendment as a major barrier to its effort to join the World Trade Organization (WTO).
WTO rules prevent members from imposing such trade restrictions on other members.
Lantos, a Holocaust survivor who was born in Hungary, has often been a harsh critic of Russia.
He is in Moscow for talks with Russian officials.