Senate Democrats, driven on Monday by the massacre in Orlando, renewed an effort to stop gun purchases by people on terrorist watch lists. But they will face the same objections that dogged a failed effort in December.  

That includes opposition from Republicans and the powerful gun lobby who are concerned about Second Amendment rights, of course. But Republicans also seized on concerns from the American Civil Liberties Union and other civil rights groups about due process rights of people who have no way to challenge why they are on the lists — particularly when they have not been convicted of doing anything wrong.  

Senate Republicans echoed those arguments on the floor in December, ahead of a 45-54 procedural vote in which Republicans rejected an amendment from Sen. Dianne Feinstein , D-Calif., on the sale of guns to people on terror watch lists. House Republicans blocked similar legislation in the House that same month.  

Republicans are unlikely to abandon the argument in any renewed push to block individuals on a consolidated terror watch list from legally purchasing firearms — which could come this week during Senate floor debate on the vehicle for the fiscal 2017 Commerce-Justice-Science spending bill.  

Last December, fending off Feinstein’s amendment, Senate Majority Whip John Cornyn , R-Texas, said there were problems with the list maintained by the federal government and said it could deny Second Amendment rights without notice and opportunity to be heard.  

“This is not the way we are supposed to do things in this country,” Cornyn said during the floor debate. “If you think that the federal government never makes a mistake and that presumptively the decisions the federal government makes about putting you on a list because of some suspicions, then you should vote for the senator’s amendment. But we all know better than that.”  

A December blog post from Hina Shamsi, director of the ACLU National Security Project, said that the no-fly list — one of the lists Democrats have wanted to use for the ban on gun purchases — could be used but not without “major reforms.”  

The no-fly list is a subset of the government’s terrorist screening database administered by the FBI. The ACLU filed a lawsuit over the no-fly list and the lack of a way for those on it to challenge it.  

Shamsi’s post quotes Speaker Paul D. Ryan ’s opposition to the effort because of the need to protect due process rights.  

“We disagree with Speaker Ryan about many things. But he’s right that people in this country have due process rights,” Shamsi wrote. “We want to see them respected.”  

Feinstein described her amendment as letting the Justice Department prevent a person from buying a gun or explosive if the recipient is a known or suspected terrorist and there is a reasonable belief that the recipient would use the firearm in connection with a terrorist act.  

Following Sunday’s Orlando nightclub shooting that left 50 people dead, Senate Minority Leader Harry Reid said the issue could come up on the floor as early this week.  

“We’re going to, as soon as we can, force a vote on this terror loophole,” Reid said Monday as the Senate convened.  

Sen. Charles E. Schumer , D-N.Y., also said one avenue for pushing the legislation is the Commerce-Justice-Science appropriations bill, which is headed to the Senate floor this week.  

The Senate version of the bill includes $29.2 billion in discretionary funding for the Justice Department, and keeps in place several longstanding Republican-backed riders on gun policies.  

It gives no ground on the White House move to add 430 agents to review background checks on firearms purchases, something Republicans have criticized over the potential for harassing law-abiding gun owners.  

“That’s one possible place to add this bill,” said Schumer, the Senate’s No. 3 Democrat. “But one way or another, we’re going to push to get the terror gap bill passed.”  

Schumer said the country is living with the consequences of the vote not to close what he calls the “terror gap” to stop attacks he says are preventable.  

“Are we going to take the painfully obvious commonsense steps and make sure that terrorists can’t get guns, or are we going to bow down to the NRA so suspected terrorists can continue to get their hands on guns?” Schumer said in a call with reporters. “If the FBI believes there is a reasonable chance someone is going to use a gun in a terrorist attack, it should be able to make that determination and block the sale.”  

Last month, Democrats criticized House Republicans for rejecting a similar amendment from House Appropriations Committee ranking member Nita M. Lowey , D-N.Y., on the House’s version of the spending bill. The vote in the Appropriations Committee was 17-29.  

At the time, Lowey referenced the San Bernardino, California, shootings in December and said that federal law prohibits nine categories of individuals from buying a firearm, but not suspected terrorists on the no-fly list. The suspects in that shooting were not on the no-fly list, but thousands are, she said.  

“We won’t let him board a plane, but we will let him buy the weaponry to carry out another mass shooting at a school, a sports arena or a government building. That makes absolutely no sense at all,” Lowey said.  

Alisha Green, Niels Lesniewski and Kellie Mejdrich contributed to this report.