Manchin didn't let up in his opposition to scrapping the filibuster.
"The filibuster is the only thing that prevents us from total insanity," he told reporters.
Democrats stepped up calls to address gun violence after a deadly elementary school shooting in Texas.
Sen. Joe Manchin of West Virginia squashed scrapping the filibuster to pass a gun control bill on Tuesday evening, arguing it's "the only thing that prevents us from total insanity."
It comes only hours after a deadly elementary school shooting in Uvalde, Texas. At least 18 children and a teacher are dead.
"It makes no sense why we can't do common sense things to try to prevent some of this from happening," Manchin told reporters at the Capitol. "It's just unbelievable how we got here as a society."
"It's just absolutely horrific," he said. "You all know where I stand; I'll do anything I can."
But the conservative Democrat did not budge on his opposition to eliminating the filibuster, saying it was the sole mechanism barring the Senate from plunging into chaos.
In the Senate, most bills need to clear the 60-vote threshold known as the filibuster to pass the upper chamber. Republicans have relied on it to block Democrats from enacting many of their major priorities, including an expansion of voting rights. Eliminating the filibuster would pave the way for bills to pass with a simple majority vote.
Manchin isn't alone in his resistance. Sen. Kyrsten Sinema of Arizona has also repeatedly objected to blowing a hole in the filibuster, casting it as an important element to foster bipartisanship.
Democrats stepped up their calls to address gun violence anew, particularly in the aftermath of a May 14 shooting at a supermarket in Buffalo, New York. A white gunman killed 10 Black people and it's being investigated as a hate crime.
"What are we doing? What are we doing?" Sen. Christopher Murphy of Connecticut said during an impassioned speech on the Senate floor. "Just days after a shooter walked into a grocery store to gun down African-American patrons, we have another Sandy Hook on our hands."
Murphy was referring to the mass shooting at Sandy Hook Elementary in Newtown, Connecticut nearly a decade ago. Twenty children and six staff members were killed in what's now the deadliest school shooting in American history.
Congress has not passed a piece of gun control legislation in a decade. Now, it doesn't seem Republicans are bound to take any steps to mitigate gun violence in America either.
"Inevitably when there's a murderer of this kind, you see politicians try to politicize it, you see Democrats and a lot of folks in the media whose immediate solution is to try to restrict the constitutional rights of law abiding citizens," Sen. Ted Cruz of Texas told reporters on Tuesday evening.