WASHINGTON — The slaughter in Florida and an attention-grabbing filibuster in the Senate did little to break the election-year stalemate in Congress over guns Thursday, with both sides unwilling to budge and Republicans standing firm against any new legislation opposed by the National Rifle Association.

Democrats renewed their call to action after Sen. Chris Murphy, D-Conn., held the floor along with colleagues in a nearly 15-hour filibuster that lasted into the early hours Thursday.

“We can’t just wait, we have to make something happen,” said Sen. Cory Booker, D-N.J., at an emotional news conference where Democrats joined family members of people killed in recent mass shootings. “These are people bound by brutality, and their numbers are growing.”

But Republicans were coolly dismissive of Democrats’ demands. Majority Leader Mitch McConnell, R-Ky., derided Murphy’s filibuster as a “campaign talk-a-thon” that did nothing but delay potential votes.

Noting that a few Democrats had skipped a classified briefing on the Florida nightclub shooting to participate in the filibuster, McConnell chided: “It’s hard to think of a clearer contrast for serious work for solutions on the one hand, and endless partisan campaigning on the other.”

Democrats spoke of the need for new gun legislation. Republicans cited the threat posed by the Islamic State group, to which Orlando gunman Omar Mateen swore allegiance while killing 49 people in a gay nightclub early Sunday. But the two sides mostly talked past each other, and efforts to forge consensus quickly sputtered out. As a result, the Senate faced the prospect of taking dueling votes beginning Monday on Democratic and GOP bills, all of which looked destined to fail.