Calling gun violence “an epidemic in our country that must be stopped,” top House Democrats introduced a bill Tuesday with bipartisan backing requiring universal background checks on gun sales, checking off a top priority for the new Democratic majority just five days into the new congressional session.

“Today is a new day,” said Rep. Mike Thompson (D., Calif.), chair of the House Gun Violence Prevention Task Force at a late-afternoon news conference where he introduced the bill alongside Speaker Nancy Pelosi (D., Calif.). “Today we’re going to take a bold first step. We’re going to honor with action all of those lives that have been lost.”

The legislation, expected to easily pass the House but unlikely to get a vote in the Senate, would require criminal background checks on any gun sale. While checks are currently required for most gun sales, some private, online, or gun-show sales can legally be completed without checks of a buyer’s record.

The bill is the first piece of national gun-control legislation with a hope of passing in even one chamber of Congress since attempts failed after the 2012 Sandy Hook Elementary School shooting in Newtown, Conn.

“Too often, sales without background checks, including unlicensed sales and online sales, have allowed guns to end up in the hands of violent criminals. By closing these loopholes and expanding background checks, we will make our communities safer,” said newly elected Rep. Lucy McBath (D., Ga.), whose son, Jordan Davis, was shot and killed in 2012.

Ten cosponsors signed on to the legislation, evenly split between Democrats and Republicans. Pennsylvania Rep. Brian Fitzpatrick, who campaigned on support for background checks and was endorsed by gun-control groups, and New Jersey Rep. Chris Smith were two of the five Republicans.

“This commonsense legislation protects the constitutional rights of law-abiding Americans while seeking to prevent felons, domestic abusers, and the dangerously mentally ill from lawfully purchasing a firearm,” Fitzpatrick said.

“Instead of looking for effective solutions that will deal with the root cause of violent crime and save lives, anti-gun politicians would rather score political points and push ineffective legislation that doesn’t stop criminals,” Jennifer Baker, director of the lobbying arm of the National Rifle Association, said in a statement.

Philadelphia-area Reps. Dwight Evans and Madeleine Dean also attended the news conference. Dean and fellow Democrats Mary Gay Scanlon and Chrissy Houlahan were elected in November.

“I’m planning to sign on, as are the other women from Southeastern Pennsylvania,” Scanlon said Tuesday. Dean and Houlahan both tweeted support.

Seen as a measure that could win bipartisan support in Congress — polls by Quinnipiac University have found between 94 and 97 percent of Americans supporting it — universal background checks have been at the top of the wish list for gun-control advocates for several years.

But public support has not led to national legislation. In 2013, after Sandy Hook, a bill expanding background checks by Pennsylvania Republican Pat Toomey and West Virginia Democrat Joe Manchin failed in the Senate by six votes.

Democrats controlled the Senate then, but the GOP had the House; it led both chambers after 2014, until last week. Gun-control bills have not moved.

“For six years, we’ve been working to find the most effective and most efficient way to save lives. … We were still blocked from holding any hearings or from casting any votes,” said Thompson.

In November, when Democrats won the House majority and some gun-control advocates ousted NRA-backed conservatives, activists rejoiced, hailing a sea change on gun issues.

A companion bill was introduced in the Senate on Tuesday by the two Connecticut senators, Democrats who have pushed gun-control legislation since the Sandy Hook shooting in their state.

“The only place this bill is controversial is in the halls of Congress,” Sen. Chris Murphy (D., Conn.) tweeted Tuesday, following with a list of 97 people who had been killed by gun violence.

Gun-control advocates hope passage in the House will put public pressure on Republican senators, but it is unlikely the GOP leadership will bring the bill to a vote.

“It is going to be difficult. We will likely have to find about a dozen Republicans who will vote with us, but there are lots of Republicans who are on the ballot in 2020,” Murphy said at a Monday news conference in Hartford, the Connecticut Mirror reported.

Toomey said in an op-ed piece published Monday in the Morning Call that Congress should enact his and Manchin’s background-checks measure. The two senators have indicated over the years that they would like to try again.

“A silver lining of Democratic control of the House is that they may pass background check legislation,” Toomey wrote. “This could boost momentum for Senate passage of my bill ... to extend background checks to cover all commercial sales, including those made at gun shows and online.”

Tuesday marked the eighth anniversary of the Tucson shooting that killed six and wounded former Rep. Gabby Giffords (D., Ariz.), who appeared with Pelosi and Thompson.

“Now is time to come together. Be responsible, Democrats, Republicans, everyone. We must never stop fighting. Fight, fight, fight!” Giffords said.

Staff writer Juliana Feliciano Reyes contributed to this story.