Democrats have long enabled the tea party movement to villainize the federal government, Sen. Charles Schumer (D., N.Y.) said in a speech Thursday. In an address at the left-leaning Center for American Progress Action Fund, Mr. Schumer said the grassroots conservative groups won over voters by convincing them that government overreach caused their economic problems — an argument Democrats have done too little to rebut. “When the tea party elite came in and said, ‘Government is your problem,’ we didn’t say: ‘No, it isn’t. It’s part of your solution,’” said Mr. Schumer, a member of Senate Democratic leadership. Tea party...