The N.R.A. has not been pressing its case alone. Mr. Trump has heard from a wide range of conservative allies who have warned him that he will imperil his re-election chances if he makes a deal with Democrats on guns.
The country’s leading gun group has been embattled this year amid internal fighting, investigations, financial strains and scandal. A revolt against Mr. LaPierre has already led to the departures of the N.R.A.’s president and its top lobbyist, as well as five board members, including the NASCAR team owner Richard Childress, who resigned this week.
Many of those who oppose Mr. LaPierre internally harbor hard-line gun rights views and want him gone before the 2020 election cycle begins in earnest. But the period after the shootings has provided Mr. LaPierre with an opening to show off the N.R.A.’s organizing muscle.
Earlier this month, he said he “opposes any legislation that unfairly infringes upon the rights of law-abiding citizens.” Willes K. Lee, the second vice president of the N.R.A. board and a key ally of Mr. LaPierre, went further, tweeting recently that “Nothing short of disarming America satisfies @democrats. Give them NOTHING,” and even promoting the hashtag “#allguncontrolisracist.”
This year, the House passed its first two significant gun control measures in a quarter century. One of the bills would require background checks at gun shows and on internet sites, where private buyers and sellers can arrange to meet in person to complete a sale. A second bill would increase the waiting period if a potential buyer does not immediately pass a background check, a measure aimed at closing a loophole used by Dylann S. Roof, who killed nine people in 2015 at a church in Charleston, S.C.
Those measures have stalled in the Republican-controlled Senate.
So have the so-called red flag laws, which give the police extra powers to confiscate firearms, and were the subject of a study released this week by researchers at the University of California, Davis, which said that “this urgent, individualized intervention can play a role in efforts to prevent mass shootings.”