Story highlights

Bipartisan effort is weighing different gun control proposals; debate possible this week

President Obama, many Democrats favor expanding FBI background checks to all sales

But focus of leading Senate talks, at the moment, would expand checks, but not universally

NEW: Obama chides Congress for not passing gun legislation; Newtown families lobbying

Washington CNN  — 

The leading Senate negotiations on gun control legislation favor expanding background checks, but the effort would as of now fall short of the universal approach backed by President Barack Obama and many Democrats, CNN has learned.

FBI background checks are currently required for commercial sales. The proposal being considered would expand them to gun shows and Internet sales, but would not require checks for other private transactions, according to multiple sources from both parties who are familiar with the talks.

Sources familiar with the negotiations between Democratic Sen. Joe Manchin, D-West Virginia, and Sen. Pat Toomey, R-Pennsylvania, tell CNN they exchanged proposals and ideas over the past few days and will soon get a better sense of where things stand.

Toomey joins talks on background checks

Obama made another pitch for his gun control agenda on Monday in Connecticut, not far from the town of Newtown where a December school massacre jolted the nation and prompted current efforts in Washington for stricter gun laws.

Obama, in Hartford, angrily chided lawmakers, saying overwhelming support among the American people for measures like universal background checks should force action in Congress.

His message was crafted as much for lawmakers as it was for the families of Newtown victims. They sat behind him on stage and were to travel to Washington with him on Air Force One to lobby members of Congress.

“Newtown, we want you to know that we’re here with you,” Obama said. “We will not walk away from the promises we’ve made. We are as determined as ever to do what must be done. “

The Senate is expected to begin debate as early as this week over proposed firearms legislation, but Democratic sources admit that the gun bill as currently written does not have the 60 votes needed to break any Republican filibuster.

The powerful National Rifle Association is staunchly opposed to the measure.

Putting new pressure on negotiators, a spokesman for Mitch McConnell said the Senate Republican leader would support efforts by GOP colleagues to filibuster the Democratic legislation.

Democratic leaders are hopeful that a deal on background checks that can win enough Republican support will emerge from the bipartisan negotiations.

Obama scolds lawmakers on gun control

Sandy Hook families to return to DC with Obama, lobby Senate

The working proposal between Manchin and Toomey would require background checks as well as make sellers keep a record of transactions.

Many law enforcement groups and gun control advocates view record keeping as critical to ensuring the check is enforceable and a weapon is traceable in case of a crime.

Senior Democratic aides and sources from outside groups pushing for tighter gun restrictions acknowledge that this approach is less expansive than what they want.

But they believe it would produce a better result than the other prominent negotiating track underway - requiring background checks in virtually all cases of private sales, but not mandating that records of those sales and checks be saved.

Recent polls show an overwhelming majority of Americans favor making a change to the background check system.

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CNN’s Ted Barrett, Ashley Killough and Kevin Liptak contributed to this report