“It is not just a just a resolution, it is a “War Powers Resolution” which has special rules. By voting 52-47, the Senate successfully used the War Powers Act’s special “privileged” rules. This allowed them to bypass the usual 60-vote filibuster and pass the measure with just a simple majority. It is now passed, and goes to the House.”
What privileged rule?
50 U.S.C. § 1546a — “Expedited procedures for certain joint resolutions and bills.”