President Biden’s O.C.C. pick declares her support for capitalism and community banks.

Facing a room full of United States senators — some of whom have suggested she is a communist — Saule Omarova, President Biden’s pick to lead the Office of the Comptroller of the Currency, introduced herself by declaring that she loves two things: American capitalism and community banks.

Ms. Omarova, a Cornell Law School professor, appeared before the Senate Banking Committee on Thursday, the start of what will be a tough path to confirmation as the head of the regulator overseeing national banks. Soon after her nomination, bank lobbyists began an unusually strident campaign against her, echoing critics who cited her birthplace — Kazakhstan, a former Soviet republic — as a reason to question her loyalty to the United States.

Bankers claimed that her academic writing proved that she was poised to replace the banking system with a government-run alternative. Even members of the Senate Banking Committee, where Ms. Omarova is set to appear, joined in questioning her views: The committee’s highest-ranking Republican, Pat Toomey of Pennsylvania, repeatedly demanded to see Ms. Omarova’s master’s thesis to check it for Marxist ideas.