Senate Democrats are prepping a host of gun control proposals in response to the mass shooting that killed 49 in an Orlando nightclub on Sunday, beginning with a measure to prevent suspected terrorists from buying a gun.

Democrats argue that the legislation drafted by Sen. Dianne Feinstein (D-Calif.), which they plan to offer as an amendment to an appropriations bill this week, is the “most relevant” gun control measure they could offer in response to the Orlando incident and a “painfully obvious” opening step.

Feinstein’s legislation would prevent anyone whose name appears on a list of known or suspected terrorists – such as the “no-fly” list – from purchasing a firearm or explosives. Presently, there is no legal barrier to such individuals buying a firearm, and individuals on terror watch lists who try to buy firearms are successful in over 90 percent of cases,  according to the Government Accountability Office. The proposal also would give the attorney general the power to block firearms transfers to anyone with known or suspected links to terrorism or anyone who might use a firearm to engage in terrorism, even if that person is not already on a list.

Had Congress earlier passed legislation to prevent suspected terrorists from buying a gun, Democrats argued, it possibly could have prevented the tragedy in Orlando. It is unclear if Mateen, however, was on that list.

“These attacks are preventable. Mass shootings are the status quo because Congress has voted against sensible gun safety measures – it’s that simple,” said Sen. Charles E. Schumer (D-N.Y.), calling the terror list proposal “a logical, and first, and mostly likely-to-pass step.”

Democrats are hoping that the severity of the Orlando tragedy compels several Republican senators to warm to Feinstein’s bill, which failed to gain enough votes to pass when it was last presented it in the wake of the deadly terror shooting in San Bernardino, Calif.

“We believe we’ll do better than we did last time,” Schumer said.

But there is no sign that enough Republicans who opposed such gun control measures in the past are now ready to change their stance.

Feinstein argued Monday that passing her legislation is “the least we could do to reduce the risk of terror attacks on our country,” but added that “I don’t know what it will take to change the mindset of this Congress.”

The Senate last rejected Feinstein’s proposal in December.

“Now, we’re living with the consequences of that vote,” Schumer said, though he admitted there was no way to be sure if that prohibition would have prevented the Orlando shooter, Omar Mateen, from getting his hands on a gun.

Mateen was on the FBI’s radar screen long before he reportedly declared his loyalty to the Islamic State during a 911 call as he shot scores of young men and women at The Pulse, one of the city’s most popular gay bars. The FBI once investigated him for comments supportive of Islamic groups and he was later investigated for loose ties to another Florida man who became a suicide bomber in Syria. In both cases, investigators found no evidence of wrongdoing. When Mateen applied to purchase the guns that appear to have been used in the attack, including an assault-style semiautomatic rifle, his record was clean.

Democrats on Monday said they will also be looking to impose a ban on assault weapons as part of their Orlando response. They expect to present that proposal after addressing Feinstein’s measure.

They also are planning legislation to stiffen background checks, deal with mental instability and address spousal abuse. On Monday, Sen. Bob Casey (D-Pa.) released a bill that would prevent people who have committed a hate crime from purchasing a firearm.

But Democrats feel Feinstein’s bill is the best proposal to lead with in the debate over how Congress should respond to another mass shooting.

“Our priority this week should be this terrorist gap measure because it is linked so directly to the issue of terrorism and extremist violence in this nation and abroad,” said Sen. Richard Blumenthal (D-Conn.), calling it a “remedy to exactly the kind of issue that is raised by the Orlando massacre.”