Their reluctance was an indication of just how toxic the gun debate has become after the Connecticut shootings, as gun control advocates push for tougher restrictions.

Nationwide, at least 23,000 schools — about one-third of all public schools — already had armed security on staff as of the most recent data, for the 2009-10 school year, and a number of states and districts that do not use them have begun discussing the idea in recent days.

Even so, the N. R. A’s focus on armed guards as its prime solution to school shootings — and the group’s offer to help develop and carry out such a program nationwide — rankled a number of lawmakers on Capitol Hill.

“Anyone who thought the N.R.A. was going to come out today and make a common-sense statement about meaningful reform and safety was kidding themselves,” said Representative Mike Quigley, an Illinois Democrat, who has called for new restrictions on assault rifles.

Mr. LaPierre struck a defiant tone on Friday, making clear that his group was not eager to reach a conciliation. With the N.R.A. not making any statements after last week’s shootings, both supporters and opponents of greater gun control had been looking to its announcement Friday as a sign of how the nation’s most influential gun lobby group would respond and whether it would pledge to work with President Obama and Congress in developing new gun control measures.