Senators in favor of gun control have rolled back their proposals, but they still don't have enough votes. (AP Photo/Ricardo Moraes.)

So here’s the state of play on the gun control package, which has been subject to intense internal debate in Washington as most of the nation focuses its attention on the horrible bomb attack in Boston: A decent bill still exists, but is being weakened almost literally by the hour.

Right now, the point of contention is on background checks. The original legislation passed out by the Senate Judiciary Committee required near-universal background checks on all weapons transfers, with only very narrow exemptions for immediate family members and short-term transfers at gun ranges and the like. Critically, it also required that dealers keep a record of all those transactions, to help ensure the checks were being conducted and to help track guns used in crimes.

That wasn’t going to fly in the Senate, so Senators Joe Manchin and Pat Toomey came up with a compromise: background checks would be required at all gun shows and intrastate online sales (interstate online sales are already subject to background checks), and their compromise would also keep record-keeping requirements. It’s just that virtually no personal transfers would be subject to a check.

Mayors Against Illegal Guns and other gun control groups backed this compromise, though some criminologists wondered if it would just push the black market for guns even further into the shadows. The ACLU backed it, because it addressed some concerns they had about record-keeping in the original legislation.

Alas, this too seems to be too proactive for the Senate to pass. Most whip counts show only 52 votes for Manchin-Toomey, eight short of the 60 presumably needed to pass. Six red-state Democrats are uncommitted, as are three Republican Senators: John McCain, Dean Heller and Kelly Ayotte. (As Greg Sargent notes, however, it’s not immediately clear if these Senators would actually filibuster Manchin-Toomey or just vote no once a vote is ordered.)

Now a new compromise is being floated: yet another exemption that would allow any gun buyers who live over one hundred miles from a licensed federal firearms dealer to forgo any background checks. The idea is to attract the support of rural-state Senators, particularly in Alaska and North Dakota.

Frankly, this isn’t a huge problem from a gun control perspective: There are licensed dealers everywhere. Running the zip code of Homer, Alaska through the GunBroker.com database shows two dealers in close range. Homer’s population is 5,003, and is located far out on the Kenai Peninsula, surrounded mostly by a national park:

But Democratic Alaska Senator Mark Begich said Wednesday this still doesn’t address his concerns. “It’s not going to seal the deal,” he told The Hill.

So this is where things get really dangerous. The question is: How low is the Senate willing to go? Senator Tom Coburn is pushing a “compromise” that renders background checks virtually meaningless: transferees could use an online portal to self-check themselves, print out the approval, and bring it to a firearms dealer. It would also forbid any records of these checks.

For many gun control groups, that’s a bridge too far. Manchin-Toomey is as far as they’re willing to go. “This is where we will hold the line,” the Coalition to Stop Gun Violence said in a statement. “Attempts by the gun lobby and their Republican allies in Congress to further water down gun violence prevention will be met with determined resistance by our coalition and its supporters in the day ahead.”

If Republicans and moderates coalesce around Coburn’s “compromise,” the gun control debate gets really ugly. Activist groups will likely reject it, and perhaps many Democrats will as well. Then what?

Even if that debate is resolved satisfactorily, the NRA is still going to attempt to gut the straw purchasing language, creating an almost impossibly high burden of proof for prosecutors. Then there’s the amendments, which are in danger of becoming poison pills if passed: concealed-carry reciprocity, for example, would require every state and municipality to respect the gun laws of other localities, which in effect would vitiate every local gun law.

In the coming hours and days we’ll learn more about these proposed changes to the gun control bill, and a Senate debate will probably start Wednesday. This is where the most public attention is needed, because the whole package could be reaching a tipping point: from weak but effective to meaningless and possibly counter-productive. 

For more information on the issues at stake, see George Zornick's cheat sheet on the main components of the gun control package.