The National Security Agency called for a "top secret" meeting with members of the House on Tuesday to lobby against the first House amendment to challenge the agency's authority to cull broad swaths of communications data, according to an invitation circulated in Congress.

The amendment was authored by Rep. Justin Amash, a libertarian Republican from Michigan, and cosponsored by former chairman of the House Judiciary Committee and liberal Michigan Democratic Rep. John Conyers. The House ruled the amendment in order on Monday, and it is expected to get a vote sometime this week.

NSA head Gen. Keith Alexander scheduled a last-minute, members-only briefing in response to the amendment, according to an invitation distributed to members of Congress this morning and forwarded to HuffPost. "In advance of anticipated action on amendments to the DoD Appropriations bill, Ranking Member C.A. Dutch Ruppersberger of the House Intelligence Committee invites your Member to attend a question and answer session with General Keith B. Alexander of the National Security Agency," reads the invitation.