Senate Democrats are set to roll out legislation this week that would block a gun from being sold without a background check.

"Senator [Richard] Blumenthal and I are going to join together to introduce what we think is a modest measure to just assure that no guns get sold to people who can't pass a background check," Sen. Chris Murphy (D-Conn.) said from the Senate floor.

The two senators are expected to join with a handful of their Democratic colleagues to unveil Blumenthal's legislation on Wednesday that would close a loophole that allows a retailer to sell a gun without a background check after 72 hours.

Murphy added that while some stores, including Wal-Mart, require a background check, "unfortunately many other retailers take advantage of a loophole that allows for 72 hours to pass without a background check, which then allows them to sell a gun."

The Connecticut Democrat's remarks come in the wake of a gunman killing nine people at a community college in Oregon late last week, though the senator cited a string of shootings in recent years.

Separately from Murphy's effort, Minority Leader Harry Reid (D-Nev.) told reporters earlier Tuesday that Senate Democrats would be rolling out a new gun control program on Thursday, though he declined to go into details.

"We're going to make sure this is inclusive, that all my caucus is involved in this, and we're not going to outline stuff here today," he said.

While Murphy said that he is "hopeful" the Senate will take up his bill, any gun control measure faces an uphill fight in the Senate.

The 2013 Manchin-Toomey background check legislation — introduced after the Sandy Hook Elementary School massacre that left 28 dead — failed to overcome a 60-vote procedural hurdle, with many red-state Democrats voting against it at the time. A handful of those lawmakers have since been replaced by Republicans, who have shown little appetite for passing a new bill.

Instead, Sen. John Cornyn (R-Texas) is working on a mental health bill and said he hopes "to have something to announce here before long."

The Senate's No. 2 Republican is also reaching out to his Democratic colleagues, adding that "[if] people don't like it, if they think it doesn't go far enough, then I would love to see their suggestions."

Murphy and Reid have been both outspoken advocates for new gun control legislation and vocal critics of Congress's inability to pass a proposal.

Murphy on Tuesday said that congressional inaction is sending a message that "we don't care."

"If we can't do something, something — a background check law, mental health bill, more resources for law enforcement — if we can't do anything to try to stop this soul-crushing, life-extinguishing violence, then we might as well as just go home," he added.