Sen. Dianne FeinsteinDianne FeinsteinTrump's Democratic tax dilemma Feinstein: Trump immigration policies 'cruel and arbitrary' The Memo: Could Trump’s hard line work on North Korea? MORE (D-Calif.) said Sunday that last week's shooting at a Colorado movie theater was further evidence that her signature assault weapons ban legislation should be renewed, pointing to gunman James Holmes's 100-round rifle magazine used in the attack.

"Weapons of war don't belong on the streets," Feinstein said on Fox News. This is a powerful weapon, it had a 100-round drum; this is a man who planned, who went in, and his purpose was to kill as many people as he could in a sold-out theater. We've got to really sit down and come to grips with what is sold to the average citizen in America.”

“I have no problem with people being licensed to buy a firearm, but these are weapons that are only going to be used to kill a lot of people in close combat," she said.

The assault weapons ban expired in 2004. 

But Sen. Ron JohnsonRon JohnsonCEOs revolt against Trump over Charlottesville GOP senator: Trump hasn't 'changed much' since campaign Senators push for possible FCC enforcement over Lifeline fraud MORE (R-Wisc.), appearing alongside Feinstein, said such legislation would do little to curtail mass killings and instead would "reduce America's freedom."

"I don't think society can keep sick demented individuals from obtaining any type of weapon to kill people," Johnson said. "This isn't an issue about guns, this is really just an issue about sick, demented individuals."

Feinstein said her legislation carried reasonable exceptions for guns that could be used for hunting or self-defense, but that high-capacity magazines like the ones used in the Colorado shooting had little use other than to injure scores of people.

"Why do you need this?" Feinstein said of such weapons.

The California lawmaker also urged President Barack ObamaBarack ObamaCongress needs to assert the war power against a dangerous president CNN's Don Lemon: Anyone supporting Trump ‘complicit' in racism DOJ warrant of Trump resistance site triggers alarm MORE and Republican presidential candidate Mitt Romney to give the assault weapons ban "a lot of consideration."

But Johnson said that he didn't believe there was a "solution here in Washington" to the problem of mass violence, and said he objected to the use of the tragedy to push legislation.

"I would hate to see a tragedy like this to promote a political agenda to reduce America's freedom," Johnson said.

The pair also disagreed over whether, as Rep. Louis Gohmert (R-Texas) suggested last week, an armed audience member could have saved some of the victims by returning fire.

"If a responsible individual had been carrying a weapon, maybe - maybe - we could have prevented more deaths," Johnson argued, drawing quick rebuke from Feinstein.

"And maybe you could have had a firefight and killed more people," Feinstein said.

But the California lawmaker seemed to acknowledge that there was little traction for new gun legislation, however, saying she saw "no outrage" building after the attacks.

"It's a very hard issue because the gun organizations go out to defeat people in the states that they can," Feinstein said.