The gun control measures President Obama announced yesterday would make the biggest changes in federal firearms laws since 1968, but administration officials emphasized one above all: closing loopholes that allow gun purchasers to avoid background checks. That emphasis involves both political and substantive calculations, the Los Angeles Times reports. Politically, administration officials believe that toughened background checks, something the National Rifle Association has opposed for years, could become a wedge that splits the opposition.

The goal would be to separate the NRA and its most ardent supporters in Congress from others who have voted against gun control measures in the past but who may now agree with Vice President Joe Biden that "the world has changed, and it's demanding action." "If you look at the combination of likelihood of passage and effectiveness of curbing gun crime, universal background checks is at the sweet spot," said Sen. Charles Schumer (D-NY).  Many experts believe that toughened background checks, particularly if coupled with a federal law against gun trafficking, which the administration also has proposed, could do more to limit violence than other, more ballyhooed proposals, including the assault weapons ban.