A Republican senator blocked a vote in the Judiciary Committee on whether to authorize subpoenas to the Justice Department to obtain secret legal opinions and other documents related to the National Security Agency’s program of domestic eavesdropping. The action by Senator Jon Kyl of Arizona will block the vote for a week. After the vote next Thursday, Senator Patrick J. Leahy, Democrat of Vermont and chairman of the committee, can decide whether to issue the subpoenas or use them as leverage in negotiations with the Bush administration over access to the documents.