US President Donald Trump’s plan to deter school shootings does not include his repeated calls to raise the age for buying semi-automatic rifles to 21.
But he is moving ahead with his controversial proposal to provide firearms training to school employees.
The president tweeted that there was not much political support for raising the minimum age on weapons sales.
Americans must be 18 to buy a rifle or shotgun and 21 to buy a handgun off licensed dealers under federal law.
The White House unveiled its proposals on Sunday night, almost a month after a high school shooting left 17 dead in Parkland, Florida.
The 19-year-old suspect, a former pupil, allegedly used an AR-15 semi-automatic rifle to attack Marjory Stoneman Douglas High School on 14 February.
The White House said a new federal commission on school safety would examine the age limit issue.
But Mr Trump tweeted on Monday: “On 18 to 21 Age Limits, watching court cases and rulings before acting.
“States are making this decision. Things are moving rapidly on this, but not much political support (to put it mildly).”
Speaking last month, the Republican president Trump had suggested it was a problem that Americans can legally buy assault rifles from the age of 18 yet have to wait until 21 to buy handguns.