More than two-thirds of Americans favor a ban on the sale of military-style, semiautomatic assault weapons, according to a new national poll by the Johns Hopkins Bloomberg School of Public Health -- illustrating a deepening divide in the U.S. That is the one, not between gun owners and non-gun owners, but between the public and Congress, where an assault weapons ban introduced just last week is already thought to have no hope of passage.

"This is the hardest of the hard," Senator Dianne Feinstein of California, who introduced the legislation, admitted on Sunday.

Yet even 45.7 percent of gun owners in the Johns Hopkins poll favored the ban, as did almost 68 percent of non-gun-owners living in households with guns. About two-thirds of the 2,703 survey respondents live in such a household, including 947 gun owners and 843 non-gun-owners. (In the survey, 85 percent of the non-owners in gun households were women, who tend to be less supportive of gun rights than men.) 

Survey respondents, like members of Congress, were more enthusiastic about requiring background checks on all gun buyers. Almost 89 percent of respondents, including more than 84 percent of gun owners and 74 percent of 169 National Rifle Association members in the survey, endorsed that idea. Political support for universal background checks received a big boost last week when Senator Joe Manchin of West Virginia said he would support them. An estimated 40 percent of current gun sales are made privately, with no background check at all. 

Almost 69 percent of survey respondents also favored banning the sale of ammunition clips capable of shooting 10 rounds or more without reloading.

This support for gun restrictions was notably higher than support found, in a separate Hopkins survey of 1530 Americans, for changing U.S. policies on mental illness. (This poll was done separately, the researchers said, so that respondents answering questions about mental illness wouldn't be influenced by having just responded to questions about gun control.) Sixty-one percent of 1,500 respondents in this second poll favored higher funding for mental health screening and treatment with the aim of reducing gun violence.

(Mary Duenwald and Francis Wilkinson are members of the Bloomberg View editorial board. Follow Wilkinson on Twitter.)