The N.R.A. has maintained a polite civility toward the White House, even though it insists the ban is a violation of the Second Amendment that deprives hunters and sportsmen of many high-powered rifles.
Chris W. Cox, the N.R.A's chief lobbyist, said in an interview that while the defeat of the assault-weapons ban would be one of the N.R.A's top priorities, the group's focus would be on convincing members of Congress to vote against it so that it never reaches Mr. Bush's desk. "Do we agree with the administration's position on this? No, we don't, but the real fight is going to be not at that level, but in Congress," he said.
A bill will be introduced in the Senate on Thursday by Senator Dianne Feinstein, Democrat of California, and Senator Charles Schumer, Democrat of New York, that would extend the ban for 10 years in much the same form it exists today. House Democrats expect to introduce a toughened version of the bill next week. That version, rejected by Senate Democrats as too politically risky, would significantly expand the class of banned weapons.
Mr. Schumer said he believed Mr. Bush's support could be critical in what he predicted would be a hard-fought campaign to renew the assault-weapons measure, which bans 19 types of firearms and others that meet certain criteria.
"We hope the president will not just say he supports the ban but will work to get it passed," Mr. Schumer said in an interview. "This will be a good measure of the compassion in his compassionate conservatism."
Senate Democrats ultimately decided that a stronger version of the ban would not pass muster with the White House and thus stood little chance of gaining passage, officials said. As a result, the Senate proposal will not specifically ban the Bushmaster rifle type that was used in last year's Washington-area sniper attacks. The House version would, because it includes a broader definition of an assault rifle, officials said.
"I would like to strengthen the bill" beyond what will be introduced in the Senate on Thursday, Senator Feinstein said today. "But I don't want to lose the bill, and important to that is the president's support."
Mr. Schumer said that even with the White House's public support, "I am worried that the anti-gun-control forces in the administration will conspire to kill this measure in the dead of night without a vote."
He noted that Mr. Ashcroft gave a noncommittal response two months ago when he was asked before the Senate several times whether he would support the reauthorization of the assault-weapons ban.
Mr. Ashcroft said Justice Department studies had found that the ban's impact on gun violence was "uncertain," and he said more study was needed.
The question of the gun ban's impact over the last nine years will be a crucial point of debate.
A report due to be released soon by the Violence Policy Center — a liberal Washington group that supports an expansion of the ban — examined the killings of 211 law enforcement officers from 1998 to 2001 and found that one in five were done with assault weapons, often copycat models that did not fall under the 1994 ban.
"Unfortunately, the firearms industry has been very successful at evading the ban," Kristen Rand, the group's legislative director, said. "Assault weapons remain a huge public safety problem."
Gun-rights groups insist that the assault-weapons ban has had little or no impact in fighting crime, and they maintain that their opponents are wrong to depict high-powered rifles as the weapon of choice for gangs and rampage killers.
"None of these weapons are used for crimes, and the Democrats know that," Mr. Norquist said.
For many gun owners, the issue is visceral, and Mr. Bush's stance has made the debate more emotional.
"There are a lot of gun owners who worked hard to put President Bush in office, and there are a lot of gun owners who feel betrayed by him," said Angel Shamaya, an Arizona gun owner who runs a Web site called "keepandbeararms.com."