The Trump administration on Sunday lifted sanctions against the business empire of Oleg V. Deripaska, one of Russia’s most influential oligarchs.

Congressional Democrats had tried to block the move this month, assailing it as a capitulation to the Kremlin and a key ally of President Vladimir V. Putin. But they failed to win enough Republican support to enforce the sanctions.

The Treasury Department had announced the sanctions against Mr. Deripaska, six other oligarchs and their companies in April as retaliation for Russia’s “malign activity” around the world.

Most of the sanctions went into effect, including against Mr. Deripaska personally. But their implementation was repeatedly delayed against Mr. Deripaska’s giant aluminum company, Rusal, as well as two linked firms, including EN+, the holding company that owned much of Rusal. The companies financed a sophisticated legal and lobbying campaign arguing that the sanctions would disrupt the aluminum market and damage companies in the United States and allied countries.