While more Russian children are adopted into homes in the United States each year than any other foreign nation, the overall numbers are relatively small — fewer than 1,000 out of 3,400 international adoptions in 2011. More than 7,400 were adopted by Russian families that year, according to the education and science ministry.

Still, Mr. Altshuler said a ban would be devastating. Some of Russia’s orphanages are badly overcrowded, with children institutionalized throughout their young lives, and many are ill-equipped to deal with the wide array of physical and mental problems common among the children, including fetal alcohol syndrome and congenital disabilities.

“A thousand kids per year will not go to the United States and will stay in Russian institutions with all the tragic consequences,” he said. As for members of Parliament, he said: “They are cannibals. They kill the country and they kill the children.”

Supporters of the ban say the United States government has not done enough to protect adopted Russian children and has not lived up to an agreement on heightened oversight that went into effect on Nov. 1. Though there is a strong nationalist streak in their arguments, occasionally ugly cases have generated international attention: including a 7-year-old boy sent back to Russia alone by his adoptive mother in Tennessee in 2010.

Yekaterina F. Lakhova, a member of Parliament and sponsor of the ban, said that years of working on child welfare issues led her to conclude that the international adoption process is overly profit-driven, and she said Russians should take care of their own.

“If the country is self-sufficient, if it believes in itself, you have to do it here,” Ms. Lakhova said, in an interview published by the news site PublicPost. “No normal, economically developed country gives away their children. I am a patriot of Russia.”