"We're going to win this thing," Manchin told MSNBC's "Morning Joe.” “These are good people. I've got to sit down -- there's more work that I've got to do. I've got to sit down and work with my colleagues."
"We had a good piece of legislation that would have saved lives -- will save lives," Manchin said.
The West Virginia lawmaker pointed blame at the National Rifle Association, saying the group's threat to score the vote scared off colleagues that otherwise would have agreed with the policy.
"If the NRA didn't score this, we would've had 15 more votes," Manchin said.
He also accused the gun lobby of having deliberately deceived members and the public about restrictions on the transfer of firearms between families and the creation of a national database to track gun owners.
“If you’ve got to sell a gun on the Internet to your cousin, than you need to check your family relationship," Manchin quipped.
Manchin added that colleagues shouldn't have worried that the gun control bill was being championed by the White House.
"This is a bill that was crafted by many people. It was a balanced bill. People were saying this was President Obama's bill, and you might not like President Obama — this was not President Obama’s bill. The White House was moving off their position to find common ground," Manchin said. "If we could have just had other people move off their position to find common ground."
Appearing immediately after Manchin, Sen. John McCain (R-Ariz.) said that he broke with the majority of his party because he "thought the bill was appropriate," but said he would not ask his close congressional allies, like Sen. Kelly Ayotte (R-N.H.), to change their votes.
"I talked to Kelly, I talked to many of my other colleagues, but it's up to them," McCain said. "They're grown people and they make their own decisions. I've never been one who went out and told people what they ought to do."