Sen. Harry Reid, D-Nev., has vowed to bring a gun package to the floor after recess, but according to sources following the issue, negotiators are still haggling over details on provisions that once seemed less controversial.

Negotiators have been working for weeks, for example, on a compromise on expanding the nation’s background check system. Democrats would like private sellers to maintain a paper record of transactions, like commercial dealers are obligated to do. Republicans, on the other hand, believe no record keeping is necessary and infringes on the rights of gun owners. In order to get an agreement, one side or the other is going to have to give; otherwise, it’s possible multiple senators or groups of senators could offer dueling provisions on the background check issue.

Of course, when it comes to gun control legislation ,“less controversial” is relative, despite President Barack Obama’s public urging outside Washington. There is still political risk in voting for any measure aimed at curbing gun violence, even expanded background checks or gun-trafficking provisions, especially for in-cycle Democrats from conservative states. It’s all the more risky because there is little indication the House will take up a package even if the Senate were to approve it. Even the background check piece — currently being negotiated by several senators, including Republican Tom Coburn of Oklahoma and Democrats Charles E. Schumer of New York and Joe Manchin III of West Virginia — seems to be a tough haul.

Few sources agreed to speak on the record, as they were not authorized to speak about the ongoing and delicate negotiations, but Democrats appeared to be searching for more Republican partners on a background check measure. The more GOP co-sponsors, the more likely they can win more Republican votes, and the more GOP votes, the more pressure on Speaker John A. Boehner of Ohio to bring up the bill.

But getting something to vote on is still out of reach. Some sources speculated an agreement could be found in the coming days, but others seemed less optimistic. In public statements, the principals involved in the talks have expressed tempered hope at best.

“It’s very hard,” Schumer said Sunday on NBC’s “Meet the Press.” “We’re working hard, and I’m very hopeful that we can get this passed.”

Coburn, who has been doing town hall meetings with constituents over the recess, also broached the issue. He is largely viewed as the key piece to the talks and has said that his chief concern is whether records of sales will be kept.

“I don’t think it’s wrong for me not to want to sell my gun to a felon — Right? Everybody agree with that? — and I don’t think I want to sell my gun to somebody that’s mentally impaired,” Coburn said in Oklahoma, according to a local account. “So if we can fix that, where it’s easy for me as a gun owner to know I’m not selling my gun to a felon or somebody that’s mentally impaired, with no records kept, I have no problem with trying to do that. And that’s what I’ve been trying to do for the last three months.”

Meanwhile, the search to find other Republican supporters is on. GOP Sens. Jeff Flake of Arizona and Susan Collins of Maine have been approached to gauge their support. Democrats and Republicans alike are trying to avoid the term “universal” when describing the proposed background check legislation for fear of alienating potential conservative backers, and public comments from Flake last week help explain why.

Flake, who also appeared Sunday on “Meet the Press,” told NBC: “We do need to strengthen the background check system. … But universal background checks, I think is a bridge too far for most of us.”

In a statement provided to CQ Roll Call, Collins’ office said she could support strengthening background checks as long as a registry component was not included.

“Senator Collins has said that she is strongly opposed to a national registry of gun owners. She would support carefully crafted language to strengthen background checks with improved state reporting to the database of felons and those who have been adjudicated by a court as having a serious mental illness that would pose a danger to the individual or others,” Collins spokesman Kevin Kelley said. “Legislation must also include mental health care reform so that we as a society can better identify and care for these troubled individuals.”

Democrats contest that the current language they have, requiring private sellers to keep a paper record of their sales, does not create a national registry but rather imposes the same rules that commercial sellers face on everyone.

Leadership aides expect any gun package would be on the Senate floor for at least a week, assuming details are ironed out as they cautiously expect.

A spokesperson for Schumer declined multiple attempts for comment on the status of the talks.