As Congress grapples with the measures the White House today proposed to combat gun violence–including a ban on assault weapons, strengthing background check laws, and enhancing mental health services–there will be dozens of gun rights lobbyists at the ready, most of them paid by the National Rifle Association. Many have been through Washington's revolving door.

In 2012, gun rights groups hired ten outside lobbying firms to help bolster their reach, according to Influence Explorer. Over all, 42 lobbyists, of whom at least more than half are revolvers, including one former member of Congress, helped spread gun rights' groups message. In contrast, gun control groups hired one outside firm and had eight lobbyists on payroll, at least two of whom had been through the revolving door.

MORE: For data on the gun debate, see the Sunlight Foundation's resource page.

Most of the firepower belongs to the NRA and its lobbying arm, the NRA Institute for Legislative Action, with 28 in-house and for-hire lobbyists, accounting for two thirds of the gun rights lobbyists. The group hired six outside lobbying firms to bolster its own lobbying forces, according to Influence Explorer. Most of the revolver power comes from the firms for hire, a number with ties to Democrats.

• C2 Group. Jefferies Murray worked as chief of staff for former Rep. Bud Cramer, D-Ala. D. Patrick Robertson was deputy chief of staff for Sen. Jay Rockefeller, D-W.Va. 
• Cauthen, Forbes, & Williams. Jeff Forbes has worked for Sen. Max Baucus, D., Mont., the Democratic National Committee, and the Clinton White House. Libby Greer was chief of staff for former Rep. Allen Boyd, D-Fla.
• Crossroads Strategies. This firm, also hired by the hunting group Safari International, includes John Green, who worked in the 1990s for former Sen. Trent Lott, R-Miss.; G. Stewart Hall, who worked for Sen. Richard Shelby, R-Ala.; Hunter Moorhead, a former staffer on the House Agriculture and Senate appropriations committees as well as Sen. Thad Cochran, R-Miss.; and Matt Wise, who worked for former Rep. Mary Fallin, a Republican who is now governor of Oklahoma.
• Prime Policy Group. Vickie Walling was chief of staff for former Rep. John Tanner, D-Tenn.
• Shockey Scofield Solutions. John Scofield worked for the House Appropriations Committee; Jeffrey Shockey is an alumnus of the same committee. 
• SNR Denton. Todd M. Weiss worked for former Sen. (and former GOP presidential candidate_ Rick Santorum, R-Pa., as well as for Sen. Tim Hutchinson, R-Ark., whose brother, former Rep. Asa Hutchinson, R-Ark., is serving as the NRA's point man on its campaign to battle gun control in the wake of the Newtown school massacre.

However, other gun rights groups also hired lobbyists with powerful connections. For example, National Shooting Sports Foundation's hires included former Rep. Max Sandlin, D-Texas.

The only gun control group to hire outside lobbyists in 2012: Mayors Against Illegal Guns. The group, backed by New York City's billionaire mayor, Michael Bloomberg, hired the Raben Group, whose lobbyists include Mark Glaze, who worked for former. Rep. David Skaggs, D-Colo., and Karen Marangi, a former Senate Judiciary Committee staffer who also worked for Sen. Patrick Leahy, D-Vt.