The answer is simple: An elected official is much more likely to lose office because he voted for regulating guns than because he voted against it. Opposing the Second Amendment is a losing issue.

Via the National Review:

Everyone knew, after the massacre in Las Vegas, that gun control was not going to get anywhere. The public conversation about guns hit the usual notes — its very roteness is by now one of those notes — but this time more of it focused on why gun control has such poor prospects.

None of these explanations grapples with is a fact that politicians in both parties know well: There are many more intense, relatively single-minded supporters of gun rights than opponents of it. An elected official is much more likely to lose office because he voted for regulating guns than because he voted against it.

Read more here.