The legislative framework, by 10 Republicans, nine Democrats, and one independent senator, contains six proposals focusing on mental health plus three gun-specific proposals that include targeting criminals who illegally evade licensing requirements and cracking down on those who illegally purchase and traffic guns.
The proposal does not raise the age limit to purchase semiautomatic assault-style weapons -- but for buyers under 21 years of age, it "requires an investigative period to review juvenile and mental health records, including checks with state databases and local law enforcement."
"Our plan increases needed mental health resources, improves school safety and support for students, and helps ensure dangerous criminals and those who are adjudicated as mentally ill can't purchase weapons," the 20 senators in a statement.
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Officials caution that the framework, which members have been negotiating for weeks, is not yet in its final form. Although the backing of 10 Republicans would give the current framework enough votes to overcome its biggest hurdle in the Senate, it's not clear if the final proposal will have the same support.
Some experts ABC News spoke with praised the current proposal for its focus on mental health, which includes making major investments to increase access to mental health and suicide prevention programs, as well as investments in programs that increase access to mental and behavioral services via telehealth, and support for state crisis intervention orders.
"The fact that it brings together a multi-tiered set of interventions in schools and communities and families as well as safety provisions ... the comprehensiveness of this is what I feel most hopeful about," said Dr. Andy Keller, president of the Meadows Mental Health Policy Institute, who advised at least one of the senators who sponsored the bill.
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But other experts said it's far from certain that the measures, had they already been in place, would have prevented the deaths of 19 children and two adults in Uvalde last month.
Retired brigadier general Dr. Stephen Xenakis, a former army psychiatrist and senior adviser to the Defense Department, told ABC News that the proposal's investment in children's and family's mental health services might have helped mitigate the attack, since there's "considerable evidence" that accused shooter Salvador Ramos had mental health problems.
"Proactive outreach and engagement could have gotten him into treatment and avoided the deterioration leading to the shootings," Xenakis said.
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The same holds true for the proposal's protections for victims of domestic violence and funding for school-based mental health support services and telehealth services.
"[If he was] a victim of abuse ... had the mental health system and protective services engaged early, he may have been diverted from becoming a shooter," said Xenakis. "He clearly had problems in school, and would've been helped by school-based mental health and wraparound services."
James Densley, a professor of criminal justice who cofounded the Violence Project, a nonprofit, nonpartisan research group that studies mass shootings, said that successful treatment comes from ease of access.
"You want to remove as many barriers as possible to getting people the help they need," Densley, who called the legislative proposal a "step in the right direction," told ABC News. "You put [a mental health clinic] right in the school, where that kid walks through the door every day and it's right there, and if it's accessible and affordable, then you're going to get more of an uptake."
But former FBI agent Mary Ellen O'Toole, a leading expert in profiling criminals' brains, said that even with all the proposals in force, Ramos could still easily have fallen through the cracks.
"Where he would have fallen through the loop was, he was not in school -- he was he was at work," O'Toole told ABC News. "He wasn't in a position where someone that knew him could have reached out and tried to get him mental health care ... through the school system."
In addition, said O'Toole, for him to have been directed toward mental health assistance that might have prevented the shooting, those around him would have needed to be aware of the warning signs.
Speaking about the people close to him -- "whether they worked in that fast food restaurant with him, or if his grandparents were aware of it" -- O'Toole said that "if you don't have something specifically designed to teach people how to recognize the warning behaviors ... he still could have gotten away with it."
Xenakis praised the proposed funding for school safety resources, including additional training for school personnel and students, but said he would also like to see "expanded school violence prevention that includes identifying students at risk for such behaviors."
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Regarding the proposal's gun-safety measures, Xenakis said that if Ramos had not availed himself of the proposed mental health services, it's not clear they would have helped avert the attack.
For gun buyers under 21 years of age, the framework proposes an enhanced review process that requires an investigative period to review juvenile and mental health records, including checks with state databases and local law enforcement -- but that would have only impacted Ramos' ability to buy a weapon had he sought out mental health assistance or had a criminal record.
"This provision with background checks could've been protective ... if he had had treatment and been involved in a mental health program," Xenakis said.
And since Ramos purchased his AR-style weapon legally, the proposal's crackdown on criminals who illegally evade licensing requirements would not have applied to him, said Xenakis.
School safety experts like Ron Avi Astor say that's why more gun safety provisions are needed. Astor, part of a group of researchers who recently issued an eight-point plan for immediate government action to reduce gun violence, told ABC News that without a bill that focuses on responsible gun ownership, there is going to be little impact on the number of shootings that occur.
Astor, who supports gun education, safety training, and stricter licensure for gun owners, said "that's where you're going to get the biggest difference: if you implement even the licensing alone, not even background checks."
"If we were willing to go for licensing like we do with cars, that would save potentially tens and tens of thousands of lives," Astor said.
The current Senate proposal "is not a perfect solution that's going to solve the problem," said Densley. "It might make these types of mass shootings less frequent. It might make them less deadly in the coming years. But it's not going to solve the problem."
The number of people injured or killed does not include the suspect or perpetrator. These graphics show the number of victims across all mass shootings from the last five years.