Anderson Cooper anchors "AC360" from Aurora, Colorado, scene of the deadly movie theater shooting, at 8 and 10 ET Friday night on CNN.
(CNN) -- The extreme carnage at the Colorado movie theater, now one of the worst mass shootings in U.S. history, reopens the nation's passionate debate about gun control -- or gun rights -- and both sides were readying for renewed legislative efforts in the aftermath of Friday's shooting.
"We're going to see the gun control side talk about how more gun control is needed in wake of this horrible shooting," said John Velleco, director of federal affairs for of Gun Owners of America.
He added that gun-control advocates should acknowledge that "more gun control could actually make situations worse by making it harder for law-abiding folks to own and carry guns, which means for lunatics that there are more unarmed, potential victims."
Meanwhile, the Brady Campaign, the nation's largest citizens' lobby to prevent gun violence, pledged aggressive action.
"Today we are meeting with activists across this country as we continue to call on the American people to add their voice for change through our petition against arming dangerous people," President Dan Gross said in a statement Friday.
"We are insistent that our elected leaders take action to prevent future tragedies. Political cowardice is not an excuse for evasion and inaction on this life-and-death issue," Gross said.
Gun-control advocates admit that any reform faces a difficult path in a sharply divided Congress -- on top of a presidential election year.
"I would hope we would see something in the Senate," Ladd Everitt, a spokesman for the Coalition to Stop Gun Violence, said about gun-control measures emerging from the Democrat-led chamber.
But the Republican-controlled House is a different story, he said.
"We don't live in a fantasy world and we understand that in the House it's a much tougher lift. The House has moved too far to the right that it's essentially a subsidiary of the NRA," or the National Rifle Association, he told CNN.
Velleco of Gun Owners of America said he has yet to see any new legislative proposals from gun-control advocates -- who he described as "kind of like vultures to take advantage of a situation to further an agenda that doesn't get traction and that people don't support."
Democrats including President Barack Obama know that the National Rifle Association, the nation's pre-eminent gun-rights group, can influence swing states against candidates who threaten the NRA's advocacy of the Second Amendment.
"The NRA is an extremely powerful organization and they deliver votes and they deliver money," said Jim Manley, a former Democrat strategist who now works for QGA, a public affairs group in Washington. "For many Democrats, it's smart politics not to get into the gun-control debate."
The NRA wasn't immediately engaging in legislative talk in the shooting's aftermath Friday: "Our thoughts and prayers are with the victims, their families and the community. NRA will not have any further comment until all the facts are known," spokesman Andrew Arulanandam said in a statement.
But at its annual meeting in April, NRA CEO Wayne LaPierre told member that his group is going to deliver a "loud and clear" message to Democrat Obama.
"When we're done speaking out, sir, gun owners will have made the difference in key precincts in battleground states," LaPierre said, "and you'll have us to blame for your defeat in November!"
New York Mayor Michael Bloomberg, who says his state has one of the nation's toughest gun control laws, on Friday challenged both Obama and presumptive Republican presidential nominee Mitt Romney to directly address gun issues.
"You know, soothing words are nice, but maybe it's time that the two people who want to be president of the United States stand up and tell us what they are going to do about it, because this is obviously a problem across the country," Bloomberg said.
"There are so many murders with guns every day, it's just got to stop," Bloomberg . "No matter where you stand on the Second Amendment, no matter where you stand on guns, we have a right to hear from both of them concretely, not just in generalities -- specifically what are they going to do about guns?"
Former Los Angeles Police Chief William J. Bratton told CNN Friday that the country needs "some sanity in our gun control laws."
"Gun control can reduce these numbers of incidents," said Bratton. "These incidents will continue to occur. We are a country in love with our guns."
He said the suspect in the Colorado mass shooting should not have had access to the AR-15 rifle police suspect he used.
Bratton, chairman of Kroll Advisory Solutions, which provides risk consulting, said he doubted Friday's incident will have much immediate impact on gun laws.
"Neither the president nor the presidential candidate or Congress have shown any interest to take on the NRA on this issue."
Friday's shooting in Aurora, Colorado, occurred during a midnight showing of the new Batman movie, "The Dark Knight Rises" -- which itself struggles with the theme of guns and violence.
CNN's JD Cargill, Phil Gast and Dana Bash contributed to this report.