House Democrats passed an assault weapons ban for the first time in roughly 30 years Friday, a legislative feat on a politically fraught issue that tested the unity of the caucus.

The historic legislation passed along party lines with a razor-thin majority and with only two Republicans voting in support. The bill faces virtually no chance of passage in an evenly split Senate.

The passage of an assault weapons ban is a significant feat for any chamber of Congress. Multiple attempts for the legislation to even be considered in committees were jettisoned. But the rise of mass shootings that have touched every corner of American life since the previous assault weapon ban expired in 2004 has catapulted the issue to a top priority for Democrats, who have long pushed for revisions to gun laws.

And more recently, a mass shooting at a Uvalde, Tex., elementary school that left 19 children and two teachers dead motivated many Democrats to push House leaders to bring the ban to the floor, according to multiple members and aides who spoke on the condition of anonymity to outline private deliberations. The House Judiciary Committee approved the bill’s passage last week, green lighting the legislation for Friday’s historic vote.

While Democrats were largely united on the principle of supporting a party-platform issue — more than 200 Democrats co-sponsored the legislation led by Rep. David N. Cicilline (D-R.I.) — competing interests between vulnerable Democrats representing swing districts and their more liberal counterparts risked its passage at several points Friday afternoon.

The fate of the ban initially was tied to a package of public safety bills that included, among other measures, community funding to curb violence and legislation dissolving a civil liability law protecting gunmakers. But an initial bipartisan proposal to double funds for local law enforcement grants issued by the Justice Department was met with skepticism from members of the Congressional Progressive Caucus and the Congressional Black Caucus. The impasse led to a delay in considering the entire package.

But overnight Thursday, members of the CBC struck a deal with Reps. Abigail Spanberger (D-Va.) and Josh Gottheimer (D-N.J.) to add language to a public safety bill that includes additional accountability measures tied to receiving the funds.

The CPC learned late Thursday night about the deal, infuriating members about not being involved in the process, according to multiple lawmakers and aides who spoke on the condition of anonymity to detail private conversations. Moreover, several members remained irate that they would have to vote to fund the police in order to vote on the assault weapons ban. Many in the liberal caucus spent Friday morning pushing to uncouple the assault weapons ban from the public safety package and hold separate votes.

Numerous civil rights groups, including the ACLU, wrote letters to Democratic leadership Friday morning asking them to not consider Spanberger’s bipartisan bill, which is co-sponsored by Rep. Tom Rice (R-S.C.).

Detaching the assault weapons ban from the rest of the public safety package, however, was risky. Numerous Democrats previously said they would vote against it or were leaning that way because they did not agree with a full ban.

But front-line Democrats were exasperated when leadership decided to postpone a vote on the public safety bills until the middle of August, instead siding with liberals to pass the assault weapons ban Friday, according to several people familiar with the group’s discussions. Many vulnerable Democrats were livid, threatening to sink a procedural vote that was necessary to pass the legislation.

Rep. Ron Kind (D-Wis.) noted the increased funding for DOJ grants is something “my folks need more of back home.”

“Last-minute legislating was never really a good way to put a package together, especially one that’s so important as this,” he said, echoing several Democrats who have raised concern over how quickly some bills are being brought to the floor by leaders. “You would hope that there would be a little more time to vet and to consider some of the problems with the legislation before they just rush it to the floor.”

Vulnerable Democratic members have been pressing leaders to consider messaging bills that would fund police departments, hoping to strip Republicans from attacking them as soft on crime. It’s a campaign message many members still feel cost them a significant number of seats during the 2020 election.

Democrats were hoping to leave Washington on a high note having just helped pass a bipartisan bill to strengthen domestic manufacturing and technology and a deal in the Senate that includes priorities on tax, climate and health-care reforms.

“We applaud Speaker Pelosi and House Leadership for advancing the Assault Weapons Ban for a standalone vote today,” said Rep. Pramila Jayapal (D-Wash.), who chairs the Progressive Caucus. “We are also pleased that this bill, which reflects the consensus of the Democratic Caucus, will move expeditiously while a separate legislative package on public safety continues to be developed and revised.”