The U.S. Senate’s strongest push in years to tighten gun control was likely to fall short on Monday while lawmakers tried to forge a compromise by later this week that might keep firearms away from people on terrorism watch lists.

The deadliest mass shooting in modern U.S. history last week has spurred quick action in Congress, but none of the four bills getting votes later on Monday was expected to achieve the 60 votes needed for passage in the 100-seat chamber, as Republicans and Democrats have not been able to reach consensus.

Republicans and Democrats have offered two proposals each to expand background checks on gun buyers and curb gun sales for individuals on terrorism watch lists after the massacre in an Orlando nightclub.

But Republicans and their allies in the National Rifle Association gun lobby say the Democratic bills are too restrictive and trample on the constitutional right to bear arms. Democrats attacked the Republicans plans as too weak, and all of the measures were expected to lose in near party-line votes.

“It’s always the same. After each tragedy, we try, we Democrats try to pass sensible gun safety measures. Sadly, our efforts are blocked by the Republican Congress who take their marching orders from the National Rifle Association,” Senate Democratic Leader Harry Reid of Nevada said as the Senate opened debate on the proposals.

Senate Majority Leader Mitch McConnell, a Kentucky Republican, said the Democratic proposals were ineffective and Democrats were not sincere in their effort.

“Instead of using this as an opportunity to push a partisan agenda or craft the next 30-second campaign ad,” McConnell said, Republican senators “are pursuing real solutions that can help keep Americans safer from the threat of terrorism.”

While gun control efforts failed after mass shootings at an elementary school in Newtown, Connecticut, in 2012 and a conference center in San Bernardino, California, in 2015, some senators see resistance to gun restrictions softening as national security looms larger in the debate.

The Orlando gunman, Omar Mateen, pledged allegiance to the militant group Islamic State as he killed 49 people in a gay nightclub.

A Reuters/Ipsos poll conducted last week found that 71 percent of Americans favor at least moderate regulations and restrictions on gun sales. That compared with 60 percent in late 2013 and late 2014.