Originally Published: 23 JUN 22 05:17 ET

Updated: 23 JUN 22 05:55 ET

By Clare Foran, Lauren Fox, Ali Zaslav and Ted Barrett, CNN

(CNN) -- The Senate is poised to take a critical vote on Thursday to advance a major bipartisan gun safety bill toward final passage. The vote is expected to succeed with Republican support, putting the legislation on a path to pass the Senate as soon as this week.

The bipartisan gun deal represents the first major federal gun safety legislation in decades. It includes millions of dollars for mental health, school safety, crisis intervention programs and incentives for states to include juvenile records in the National Instant Criminal Background Check System.

It also makes significant changes to the process when someone ages 18 to 21 goes to buy a firearm and closes the so-called boyfriend loophole, a victory for Democrats, who have long fought for that.

The package amounts to the most significant new federal legislation to address gun violence since the expired 10-year assault weapons ban of 1994 -- though it fails to ban any weapons and falls far short of what Democrats and polls show most Americans want to see.

A critical vote that requires GOP support

Thursday's vote will be held to overcome a GOP filibuster and requires 60 votes to succeed, meaning that at least 10 Republicans must join with Democrats to vote in favor.

That is expected to happen, however, after 14 Republicans voted to advance the bill in an initial vote Tuesday evening.

Once the Senate breaks a filibuster, it will pave the way for a final passage vote.

Senate Majority Leader Chuck Schumer has called to pass the bill this week, though the exact timing of a final vote is still to be determined. A final Senate vote could come as early as Thursday if all 100 senators consent to a time agreement. It will take place at a simple majority threshold.

The House would next have to take up the bill before it can be signed into law.

The legislation came together in the aftermath of recent, tragic mass shootings at a Uvalde, Texas, elementary school and at a Buffalo, New York, supermarket, which was in a predominantly Black neighborhood.

A bipartisan group of negotiators set to work in the Senate and unveiled legislative text on Tuesday. The bill -- titled the Bipartisan Safer Communities Act -- was released by Republican Sens. John Cornyn of Texas and Thom Tillis of North Carolina and Democratic Sens. Chris Murphy of Connecticut and Kyrsten Sinema of Arizona.

Lawmakers are now racing to pass the bill before they leave Washington for the July 4 recess.

The fact that bill text was finalized, and the legislation now appears poised to pass the Senate, is a major victory for the negotiators who came together to strike a deal.

The bipartisan effort appeared to be on thin ice after several key sticking points emerged, but ultimately negotiators were able to resolve issues that arose. The deal marks a rare instance of compromise across party lines on one of the most contentious issues in Washington -- a feat in today's highly polarized political environment.

Reaching a bipartisan agreement on major gun legislation has been notoriously difficult for lawmakers in recent years even in the face of countless mass shootings across the country.

"For too long political games in Washington on both sides of the aisle have stopped progress towards protecting our communities and keeping families safe and secure," Sinema said Wednesday in a Senate floor speech.

"Casting blame and trading political barbs and attacks became the path of least resistance, but the communities across our country who have experienced senseless violence deserve better than Washington politics as usual," the Arizona Democrat said. "Our communities deserve a commitment by their leaders to do the hard work of putting aside politics, identifying problems that need solving, and working together towards common ground and common goals."

Key provisions in the bill

The bill includes $750 million to help states implement and run crisis intervention programs. The money can be used to implement and manage red flag programs -- which can temporarily prevent individuals in crisis from accessing firearms through a court order -- and for other crisis intervention programs like mental health courts, drug courts and veterans courts.

This bill closes a years-old loophole in domestic violence law -- the "boyfriend loophole" -- that barred individuals who were convicted of domestic violence crimes against married partners, or partners with whom they shared children or partners with whom they cohabitated, from having guns. Old statutes didn't include intimate partners who may not live together, be married or share children. Now, the law will bar from having a gun anyone who is convicted of a domestic violence crime against someone they have a "continuing serious relationship of a romantic or intimate nature."

The law isn't retroactive. It will, however, allow those convicted of misdemeanor domestic violence crimes to restore their gun rights after five years if they haven't committed other crimes.

The bill encourages states to include juvenile records in the National Instant Criminal Background Check System with grants as well as implements a new protocol for checking those records.

The bill goes after individuals who sell guns as primary sources of income but have previously evaded registering as federally licensed firearms dealers. It also increases funding for mental health programs and school security.

GOP divided over the bill

A split has emerged among some prominent members of House and Senate GOP leadership.

Senate Minority Leader Mitch McConnell has said he supports the bipartisan gun deal. But top House Republican leaders are lining up in opposition to the bill and are urging their members to vote "no," even as the Senate moves toward passage of the bill this week.

But even with House GOP leaders opposing the bill, there are already some House Republicans who have indicated they plan to vote for it, and the Democrat-controlled chamber is expected to be able to pass the legislation once it passes in the Senate.

Speaker Nancy Pelosi has promised to "swiftly bring it to the floor" of the House once it passes the Senate, "so that we can send it to President Biden's desk."

"While more is needed, this package must quickly become law to help protect our children," Pelosi said in a statement.