President Obama angrily blamed the defeat Wednesday of his centerpiece gun-control proposal on lies spread by the National Rifle Association, calling it “a pretty shameful day for Washington.” “The gun lobby and its allies willfully lied about the bill,” Mr. Obama said in the White House rose garden about 90 minutes after the vote. “It came down to politics.” As he spoke, Mr. Obama was surrounded by family members of victims of the Newtown, Conn., school shooting. Also with him was former Rep. Gabby Giffords of Arizona, wounded in an assassination attempt. Senators voted 54-46 late Wednesday to expand background...