“The president has made clear that he intends to take a comprehensive approach,” Jay Carney, the White House press secretary, said Tuesday. Mr. Carney said the proposals were aimed, broadly, at what he called “the scourge of gun violence in this country.”

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While semiautomatic rifles were used in several recent mass shootings, including those in Newtown and in Aurora, Colo., where 12 people were killed at a movie theater in July, a vast majority of gun murders in the United States are committed with handguns.

In 2011, 6,220 people were killed by handguns, and 323 by rifles, according to the Federal Bureau of Investigation. So while the administration is expected to try to restrict some types of assault weapons, it is also focusing on ways to keep more commonly used firearms out of the hands of dangerous criminals and people with mental illness.