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“This is not 1993. The world is very different than it was back then. The Internet really wasn’t moving — it was just getting started,” Mr. Van Cleave said.

He also pointed out that nobody ever challenged the assault weapons legislation in court — something that would be much more likely now, given the Supreme Court’s rulings in 2008 and 2010 upholding an individual’s right to bear arms, though still allowing localities to impose reasonable restrictions.

But Mr. Bennett said Democrats who support gun control have become more savvy, too, over the past decade.

He said that after the Columbine shooting “we were still in an old-gun paradigm where Democrats were using some very old and outdated framing around the issue where they were basically saying anyone who owned a gun was culpable for gun crime. They’ve moved away from that sharply in the years since.”

Both sides said they expect part of the renewed debate to focus on what new classes of people should be denied gun ownership. In the Connecticut shooting, news reports have said, the 20-year-old gunman was autistic.

Indeed, the most recent gun rights flare-up was over mental health. Sen. Tom Coburn, Oklahoma Republican, tried to attach an amendment to the defense policy bill this month that would have required a ruling by a judge before a veteran could be deemed mentally incompetent to own a gun.

Sen. Charles E. Schumer, New York Democrat, blocked that effort.

While the Senate has at least held gun control debates over the past decade, the House has not.

In fact, the only gun legislation to emerge from the lower chamber in recent years was a bill to limit firearms manufacturers’ liability. That died in the Senate during the 2004 debate.