However, witnesses opposed to limits on weapons contended Feinstein's proposal would be open to legal challenge, and would give criminals who acquire weapons illegally an advantage over law-abiding gun owners.

Former Rep. Sandy Adams, R-Florida, said it was not the time for "feel-good legislation so you can say you did something."

"Taking guns from law-abiding citizens while leaving them defenseless against violent criminals, who by their very definition do not abide by the law, is not the answer and it is definitely not the right thing to do," she said in her opening statement.

The reference to "feel-good legislation" drew a rebuke from Sen. Dick Durbin, D-Illinois, who told Adams that he was sorry she used the phrase.

"I don't feel good about being here today," Durbin said. "Mr. Heslin does not feel good about being here today."

Feinstein noted that the 1994 ban was challenged repeatedly in federal courts on multiple grounds, including Second Amendment protections, and survived each time.

In his opening statement, Republican Sen. Chuck Grassley of Iowa conceded that some gun legislation would emerge in the aftermath of the Newtown killings. In particular, he said, new laws would target gun trafficking and straw purchases -- in which a legal buyer purchases firearms for other who are ineligible.

The Judiciary Committee chairman, Sen. Patrick Leahy of Vermont, was adamant Sunday that expanded background checks would not include provisions to register gun owners. But he said that responsible Americans looking to purchase firearms shouldn't fear robust checks.

To Lanae Erickson Hatalsky of Third Way, an independent policy group, what she called "political reality" means that Congress will focus more on keeping weapons out of the wrong hands instead of a new weapons ban.

That strategy reflects "an understanding of gun crime in the country," she told CNN earlier this month.

The NRA and other opponents contend that any limit on private gun ownership violates the constitutional right to bear arms. Even partial steps in that direction, such as prohibiting specific models, are considered a path to potential confiscation or other future elimination of Second Amendment rights, they argue.

In recent decades, the NRA has led lobbying efforts that shifted the discussion away from stronger gun controls -- such as an outright ban on handguns and a national registration of gun ownership pushed by top Democrats in the 1980s and 90s -- to the incremental measures under consideration now.

Erickson Hatalsky, the director of social policy and politics at Third Way, noted examples of the NRA's influence in the last significant gun legislation -- the Brady Bill of 1993 that required background checks on guns purchased from licensed dealers, followed by the limited assault weapons ban a year later.

While the Brady Bill led to the background check system in use today, the NRA made sure it didn't apply to private sales, such as those at gun shows, she said.

NRA President David Keene has said he expected few substantive changes in law because the emotional reaction to the Newtown shooting would eventually give way to common sense regarding gun rights and the wishes of American gun owners.

His organization keeps a scorecard for each Washington legislator on gun issues, and spends millions on campaign contributions to favored candidates.

In Congress, some influential Democrats join virtually all Republicans in opposing, or at least questioning, a renewed ban on semi-automatic weapons like the Bushmaster AR-15-style rifle used in the Newtown shootings.

Senate Majority Leader Harry Reid, who gets high marks from the NRA for his opposition to past gun control efforts, has indicated support for expanding background checks but refuses to endorse a new weapons ban.

According to Reid, a bill from the Judiciary Committee was unlikely to include an updated weapons ban, but he would allow a vote on the provision during floor debate.

Such a vote would amount to Feinstein's last stand on the issue.