The Lance Armstrong Foundation, the Texas-based charity known as Livestrong, sent a lobbyist to Capitol Hill last week to discuss the funding for the agency that has accused the retired cycling champion of cheating to win the Tour de France, a Congressional staff member said.

A spokesman for U.S. Rep. José Serrano (D., N.Y.), who sits on the House Appropriations Committee, said his office was visited by a registered lobbyist working on behalf of the foundation, which works to increase awareness of cancer.

The...