WASHINGTON —The U.S. Senate cleared a Republican filibuster on Thursday that is expected to open debate next week on gun control legislation that has stayed in the spotlight since the Newtown, Conn., elementary school shootings.

The Senate voted 68-31 to proceed with Sen. David Vitter, R-La., opposed, and Sen. Mary Landrieu, D-La., in support.

Landrieu says she has not decided how she will vote on the legislation and the many amendments expected to be proposed.

The most likely aspect to win Senate approval is an amendment for expanded background checks to cover all commercial and online gun sales and to end the so-called gun show loophole of buying guns at events without proper checks. That proposal would exempt criminal background checks on some private transfers of weapons, including among family members.

Other votes are expected on measures to ban some assault weapons and to limit the amount of bullets sold in ammunition clips.

Landrieu said in an interview before the vote that debate needed to begin, regardless of how she will ultimately vote on the measure.

“I’m going to be a strong supporter of the Second Amendment through this entire process, but I most certainly think the debate needs to be started,” Landrieu said. “Until I see the actual amendments in writing, I’m not going to speculate as to how I’m going to vote.”

Landrieu also acknowledged that Louisiana has the highest per capita gun murder rate in the nation.

“Gun violence in America is high, shamefully high. Our state is one of the highest, of course,” Landrieu said. “It’s not just gun violence in schools; it’s gun violence on our streets. On the other hand, I feel strongly that people should have access to rifles for hunting and outdoor sports and recreation, which is a time-honored sport in Louisiana.”

Louisiana residents recognize that there is too much gun violence in the state and nationwide, she said. “The problem gets to be when you come to decide what should we do about it and that gets a little more complicated,” Landrieu said.

Vitter declined an interview request on the topic and would not answer questions regarding expanded background checks, but he noted his opposition to gun control legislation in an email response.

“As a strong supporter of the Second Amendment, I voted ‘no’ on this gun control motion for a simple reason: I think virtually all of these measures would have real impact on law-abiding citizens but none on criminals,” Vitter wrote. “In 2010, over 15,000 felons and fugitives illegally tried to buy guns, and of those only 44 were prosecuted. Why don’t we enforce the laws already on the books?”

Progress was made Wednesday on the background checks aspect when Sens. Pat Toomey, R-Pa., and Joe Manchin, D-W.Va., reached a bipartisan agreement to support expanded background checks, even though it was quickly denounced by the National Rifle Association and many House Republicans.

Toomey said Wednesday he does not believe that improved background checks amount to gun control.

“I think it’s common sense. If you pass a criminal background check, you get to buy a gun. No problem,” Toomey said. “It’s the people who fail a criminal or mental health background who we don’t want to have a gun.”

Landrieu said the Toomey-Manchin agreement set a positive opening tone.

“I think those two leaders stepping up to try to find a way forward on background checks is a very good way to start,” Landrieu said. “How it ends, I don’t know.”