The gun reform proposal with the greatest chance of winning congressional approval is arguably the proposal that could have the most success in reducing gun violence - closing the massive loopholes in the federal background check law. This is where the White House and reasonable legislative leaders in both parties should focus their attention.

But even passing a bill that would subject most gun buyers to a review of their criminal and mental health background - which should be automatic - will require political sacrifice. Republicans, and some Democrats, from states and districts with strong support for gun rights, must be willing to risk defying the National Rifle Association to pass legislation most already know is the right thing to do.

Democratic leaders, conversely, must be more interested in finding a compromise to get legislation passed than they are excited about capatalizing politically on Republican opposition.

While we would certainly like to see a federal law passed with similar attributes to the recent Connecticut gun reform legislation - including an expansive ban on the sale of military-style rifles and large-capacity magazines - the political reality is that is not likely to happen. Passage of a comprehensive gun reform bill always faced long odds in the Senate - and approval grows more unlikely each passing day - while it has long appeared unattainable in the House.

One only has to look at what has happened at the state level to get a perspective of the politics. While the approval of gun reform laws in Connecticut, New York, Maryland and Colorado has received much media attention, more states have actually eased gun restrictions in the wake of the massacre of school children and educators at Sandy Hook Elementary School on Dec. 14, the Wall Street Journal reported.

But the idea of improving background checks - so that people with histories of domestic violence, unstable behavior or criminal activity cannot legally buy guns - has broad public support, opinion polls since the Sandy Hook attack have consistently shown.

"We have to believe that every once in a while we set politics aside and just do what's right," said President Obama during his speech Monday at the University of Hartford, where he sought to rally public support for gun reform. The challenge is reaching agreement on "what's right." A background check bill has the greatest potential for that agreement.

Republicans in the Senate appear hung up on a couple of points. Most seem ready to back a law that would subject Internet and gun-show buyers to background checks and to record of sale requirements. These purchases are now exempt, accounting for roughly 30 percent to 40 percent of sales. Many Republicans (and some Democrats) balk, however, at subjecting private sales - person to person - to the reviews. Allowing that loophole to stay open could be the price for getting a bill passed.

More problematic are overwrought concerns that universal background checks will lead to excessive government record-keeping, which some conservatives consider intrusive and a form of de facto registration. Perhaps language that limits the use and availability of that information could address those fears.

Even with compromise there is no assurance, particularly in the House, that comprehensive background check legislation will pass. But Republicans could end up paying a heavy political price if they block a reasonable bill that has such strong public support.

Legislation restoring the federal assault weapons ban and restricting access to high capacity magazines may have to await action by a future Congress, after another election has changed the political scene.