“The filibuster is simply a tactic to stop the bill from passing,” he added. “If you’re successful with the filibuster it’s over, it’s done, and that would be my preference.”

In March, a group of Republican lawmakers, led by Sens. Rand PaulRandal (Rand) Howard PaulHouse bill set to reignite debate on warrantless surveillance Authorizing military force is necessary, but insufficient GOP feuds with outside group over analysis of tax framework MORE (Ky.), Mike LeeMichael (Mike) Shumway LeeWhatever you think the Alabama special election means, you’re probably wrong How the effort to replace ObamaCare failed Overnight Regulation: Trump temporarily lifts Jones Act for Puerto Rico | Bill would exempt some banks from Dodd-Frank | Senators unveil driverless car bill MORE (Utah), Ted CruzRafael (Ted) Edward CruzWhatever you think the Alabama special election means, you’re probably wrong This week: Congress gets ball rolling on tax reform Week ahead: Senators work toward deal to fix ObamaCare markets MORE (Texas) and Marco RubioMarco Antonio RubioOvernight Defense: Tillerson, Trump deny report of rift | Tillerson says he never considered resigning | Trump expresses 'total confidence' in secretary | Rubio asks Army to kick out West Point grad Rubio asks Army to kick out West Point grad with pro-communist posts GOP establishment doubts Bannon’s primary powers MORE (Fla.), wrote to Senate Majority Leader Harry ReidHarry ReidChris Murphy’s profile rises with gun tragedies Republicans are headed for a disappointing end to their year in power Obama's HHS secretary could testify in Menendez trial MORE (D-Nev.) pledging to “oppose the motion to proceed to any legislation that will serve as a vehicle for any additional gun restrictions.”

The group counts 13 Republican signers, including Risch. Senate Republican Leader Mitch McConnellAddison (Mitch) Mitchell McConnellGun proposal picks up GOP support Children’s health-care bill faces new obstacles Dems see Trump as potential ally on gun reform MORE (Ky.) did not sign the letter but backed the effort, saying he would filibuster the bill because the background-check portion did not receive a single Republican vote during the Judiciary Committee markup. 

However, a number of senior Republicans this week said they would not support a filibuster, making it likely that Senate majority leader Harry Reid (D-Nev.) can bring the measure to debate despite the opposition.

Still, Risch and other Republicans remain opposed to any expansion of the current background checks system. Risch on Wednesday argued it would pass the burden on to legal firearms owners, and said existing laws weren’t being enforced in the first place.

Republican Sen. Pat Toomey (Pa.) and Democrat Joe ManchinJoseph (Joe) ManchinOvernight Energy: EPA aims to work more closely with industry Overnight Finance: Lawmakers grill Equifax chief over hack | Wells Fargo CEO defends bank's progress | Trump jokes Puerto Rico threw budget 'out of whack' | Mortgage tax fight tests industry clout Lawmakers try again on miners’ pension bill MORE (W.V.) will hold a press conference early Wednesday to discuss developments in their closely-watched negotiations on expanding background checks for gun purchases.

The joint press conference has raised hopes the two lawmakers are close to a deal which would be a breakthrough for efforts to pass a Senate gun control bill. A bipartisan background check measure could attract enough GOP support to reach the Senate’s 60-vote threshold.

Risch said he didn’t know the details of the potential bipartisan proposal, but said it likely would not have stopped the Newtown massacre or other mass shootings.

“I don’t know what the proposal is. I suspect it’s an expansion of the background checks system,” he said. “What we know for certain is that the atrocities that were committed at Virginia Tech by a defendant, a criminal, who actually passed a background check, and the atrocities that were committed at Connecticut were done with guns that were purchased by someone who went through a background check.

“I want to keep guns out of the hands of people that shouldn’t have them,” said Risch. “The background check, at least under the system we have today, is not a way of doing that.”