Just after 7 a.m. on a stifling morning, one day before his city's July 4 holiday celebrations, Baltimore's mayor dashed around the plaza outside city hall. Clad in a white polo shirt and sneakers, Mayor Brandon Scott, 39, ran from point to point, maneuvering between camera crews and a series of tightly-scheduled nationally televised interviews. He'd catch his breath, handle a phone call and, at one point, sprang back inside the building briefly in between appearances.

Scott is a former city council member who previously represented one of the northernmost sections of a city with a troublingly stubborn history of gun violence. He wanted to make a plea to America, and more specifically to Washington, that morning.   

"We need Congress to act on this issue," Scott told CBS News as the morning began. It's a message and phrase he would repeat at an afternoon press conference, standing with his top city officials and his acting police commissioner.

One day earlier, a sea of gunfire erupted at the 27th annual holiday week community cookout in Baltimore's Brooklyn neighborhood. At least 30 people were struck. Two of them died. Though multiple shooters and guns are suspected to have been part of the rampage, in a city with zero gun stores, only one person — a 17-year-old — has been arrested so far.

In one of his Monday interviews, Scott said 400 ghost guns were recovered in Baltimore last year. 

"And it happens because we in this country are still allowing the sanctity of American guns to outweigh the sanctity of American lives, especially our children," he said. "How more of these things have to happen before we get action at the national level?"

Though Congress is just one year removed from passing a law that enhanced background checks for gun buyers under 21 and closed a loophole to prevent convicted domestic abusers from purchasing firearms for five years, the July 4 holiday week ended with a new series of calls on Washington to do more. And not just from Baltimore's mayor.

"There is more work to do, including establishing truly universal background checks, banning assault weapons and large-capacity ammunition feeding devices, closing more loopholes related to illegal gun purchases, cracking down on gun trafficking and more," said Democratic Rep. Shontel Brown, of Ohio, on Sunday. Her comments came in the wake of a mass shooting of nine people in Cleveland, one of nearly 30 mass shootings in the U.S. already in July.

In a divided Congress, the two parties and two chambers have demonstrated little inclination toward cutting another bipartisan, bicameral agreement to change federal gun laws in 2023.  

Last month, U.S. House Democrats began an effort to force a formal debate and vote on new gun control measures through the use of a parliamentarian maneuver known as a "discharge petition."

Two of the petitions would stiffen background check requirements for firearms sales. Another would order new regulations for assault weapons. If any one of the petitions garners 218 signatures from the House's 435 members, it would force the hands of Congressional leaders to bring the gun control measures to the House floor.

One of the background check petitions had garnered 208 signatures, all from Democrats, as the holiday week concluded. But even if all House Democrats were to sign the petitions, they'd need to also secure the signatures of five Republicans.

As of Sunday, none of them had obtained a single GOP signature, signaling the effort could be destined to stall as the summer continues.

Democratic Rep. Lucy McBath, of Georgia, whose son was murdered nearly a decade ago, is leading one of the discharge petition efforts. 

"After the conviction of my son's killer, I made a promise to Jordan on the steps of the courthouse to take all the love I have as a mother and spend the rest of my life devoted to making sure parents across the country never had to go through the same pain that I did," McBath said. "It is these policies that will fulfill our promise."

When asked last month by CBS News if Republicans had indicated future support, McBath said, "I'm still hoping at some point that they'll step forward."

Several House Republican leaders did not immediately return CBS News' request for comment.

Republican Rep. Brian Fitzpatrick, of Pennsylvania, a moderate who co-chairs the Congressional Problem Solvers Caucus and who has previously spoken in support of some background checks for firearms sales, has indicated he would not support the discharge petitions in a June interview with NBC. Fitzpatrick's office did not respond to multiple requests for comment from CBS News.

Democratic Rep Glenn Ivey, of Maryland, who has held a series of news events urging House votes on gun legislation, told CBS News, "Discharge petitions may be the only way to force the House Republicans to vote up or down."  

Democratic Rep. Jennifer Wexton, of Virginia, said, "We're using every tool at our disposal."

During the two-week Congressional recess — amid the series of mass shootings in Baltimore, Fort Worth, Texas, and Cleveland — some House Democrats issued a new series of statements in support of debate on the gun control bills.

Democratic Rep. Jared Moskowitz, an alumnus of Marjorie Stoneman Douglas High School and the Congressman who represents the city of Parkland, Florida, told CBS News he continues to receive daily phone calls from constituents urging Congress to act. 

"Poll after poll shows the majority of Americans support expanded efforts to curb gun violence. If members truly represent their constituents, wouldn't they vote to support measures that the American people want and will save lives?" Moskowitz said.

Republican gun legislation is similarly stuck. During recent debate over House-passed legislation that would loosen regulations of pistol braces, devices that make some firearms easier to fire with one hand, Republicans argued the Biden administration and Democrats sought to violate Second Amendment rights. Republican Rep. Bob Good, of Virginia, accused the Democrats of having "no regard for the Second Amendment or for our disabled veterans."

House Majority Leader Steve Scalise, of Louisiana, who was himself wounded in a 2017 shooting while practicing for the Congressional Baseball Game, said, "House Republicans will always fight to protect the constitutional rights of American families." 

But with Democrats in the majority in the Senate, the pistol brace bill is just as likely to expire without becoming law as the Democrats' discharge petitions seeking tighter gun controls.

The standoff has flared several times this year. In the wake of a March mass shooting in Tennessee, some Tennessee Republicans criticized calls for new gun restrictions. Rep. Tim Burchett told CBS News at the time, "We've got a mental health crisis in this country." 

During one of his final interviews on that hot morning before the July 4 holiday, Baltimore's mayor said his city is frustrated by the "cowardice" of a Congress that appears intransigently divided on issues of gun violence, even as the scope and number of shootings soars nationwide. And he said his city isn't the only one frustrated.

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• Gun Control
• Shooting