When we compare the NRA’s 2008 contribution against PACs other than single-issue, they get positively dwarfed in clout. The top 20 PACs for the 2008 cycle all spent more than the entire gun lobby; the 20th, the National Air Traffic Controllers Association, spent $2.21 million.
Of the top 20, eleven are unions, with the IBEW coming in second place with $3.344 million, 98% of which went to Democrats. That cycle produced a Democratic President and large Democratic majorities in the House and Senate.
If “clout” was all that was in play, then surely that Congress could have passed gun-control legislation as well as Card Check for their union backers.