"I'm not afraid to say let's talk about that," he said. "I'm not afraid of the political ramifications of taking a responsible position."
Manchin, who had just returned from a family hunting trip, said he still honored long-standing West Virginia traditions of safely using guns for hunting and sport.
Manchin said he had never hunted with anyone who needed an assault rifle or clip containing more than three rounds to kill an animal. Still, a picture posted in 2009 by a gun industry website shows Manchin, then West Virginia's governor, with a gun the website identified as an AR-15, the kind of rifle authorities said was used in Friday's school shooting.
Manchin said the country needed to find a balance between recognizing safe use of traditional firearms while restricting high-power weapons designed primarily for military use.
"I will defend Second Amendment rights so long as I live," he said. "But I also believe there's a responsible, sensible way we should be conducting ourselves."
When asked whether the tragedy had led him to rethink his positions, Rep. Nick Rahall, D-W.Va., responded with a statement saying Congress needed to take action.
"I think all of us woke up to a different nation Saturday morning," Rahall said.
"The circumstances of this tragedy are so horrible that it demands aggressive action," he said. "Our state and nation share a collective desire to try to find some way to prevent such a tragedy from happening again, and, God forbid, from happening in our own communities."
Rahall did not say exactly what action should be taken. He said he wanted to hear from all sides.
"Let us act deliberately, but for the sake of too many already lost, let us act," he said.
Rep. Shelley Moore Capito, R-W.Va., said in a statement that there was "no question that Friday's devastating shootings will ignite a debate."
Capito, also A-rated by the NRA, did not comment on specifics but said lawmakers should put politics aside as they move forward.
"As legislators, it is our duty to facilitate thoughtful policy discussions in the aftermath of such a tragedy, regardless of political positions," Capito said.
"As a mother of three and grandmother to one, I certainly have serious concerns as to how someone capable of such mass murder was able to get his hands on an assault weapon and murder 26 innocent people," she said.
In a statement Monday, Rockefeller said the Newtown murders were the latest reminder that the country has not done enough to get dangerous weapons off the streets.
"Too many young lives have been taken from us too soon, and Friday's unspeakable actions are another stark wakeup call that we must do more," he said. "This is not the time for soft words and empty promises, but a call for strong action."
Rockefeller said the failure to renew the assault weapons ban in 2004 was "unacceptable." Contrary to critics, he said the ban did not go against traditional pro-gun values.
"West Virginia has a proud hunting tradition and respect for the Second Amendment," Rockefeller said. "But most hunters I talk with know that prohibiting the use of military-grade weapons or clips that can fire dozens of rounds in a matter of seconds will not impact those traditions, nor do they have a place on our streets."
Rockefeller, Manchin, Rahall and Capito also said the debate needs to be expanded to cover matters of mental health and violence in media.
"We've got to reevaluate where we are as a society," Manchin said.
"As a lifelong defender of the Second Amendment, I believe that gun safety is essential, but so is addressing the gaps in our mental health system and the issue of drugs and violence in our culture and prayer in our schools," Rahall said.
Manchin's statements prompted reporter questions about his use of a hunting rifle to shoot President Barack Obama's cap-and-trade bill in his now-infamous "Dead Aim" 2010 campaign ad.
Manchin defended that ad Monday.
"We used it in the most responsible manner," he said. "I don't think that that glorified anything."
The Associated Press contributed to this report.
Contact writer Jared Hunt at jared.h...@dailymail.com or 304-348-5148.