Now 13 Senators Promise to Filibuster Senate Gun Control Bill

Politico has this update here: Marco Rubio (R-Fla.), Ted Cruz (R-Texas), Mike Lee (R-Utah), Jerry Moran (R-Kansas), Jim Inhofe (R-OK), Richard Burr (R-NC), Ron Johnson (R-WI), Mike Enzi (R-WY), Jim Risch and Mike Crapo (R-ID), Dan Coats (R-IN), and Pat Roberts (R-KN).

UPDATE:  Of course, on the other hand, John McCain (R-Ariz.) and Lindsey Graham (R-S.C.) have said that they will oppose the filibuster.

UPDATE: Mitch McConnell (R-KY) has joined those promising to filibuster the bill.