WASHINGTON — Victims of the massacre in Newtown, Conn., had just been laid to rest when Wayne LaPierre, the chief executive of the National Rifle Association, met with his board of directors in early January. A national tide of grief had prompted new attacks on his group and a White House push for more gun control measures, while Mr. LaPierre — who had called for armed guards in every school — was pilloried as a “gun nut” on the cover of The New York Post.

“I don’t know why the N.R.A. or the Second Amendment and lawful gun owners have to somehow end up in a story every time some crazy person goes off and kills children,” he complained to Cleta Mitchell, a board member, who says Mr. LaPierre was “horrified” by the deaths and “insanely angry” that he and the N.R.A. were being blamed.

“These people are out to get us and the Second Amendment,” she recalls him telling the board, “and we’re not going to let them.”

Now, as the Senate takes up gun control measures, the no-compromise strategy Mr. LaPierre has honed over his 35 years with the association is facing its most difficult test in decades. Lawmakers may defy Mr. LaPierre by extending background checks on some gun purchases, which the N.R.A. opposes. But since that grim January planning meeting, Mr. LaPierre has prevented what he and his group feared most: bans on assault weapons and high-capacity magazines.