Candidates Address Class Size and Teachers' Unions at Education Forum Though education has not been a major focus in the presidential campaign, the charged issue of class size was injected into the race on Tuesday as Mitt Romney said that while governor of Massachusetts, he was able to do more with less during an economic downturn. He repeated assertions made during the Republican primary campaign that slightly larger classes -- a result of cuts in Massachusetts state aid to schools in 2003 and 2004 -- were not as important in student learning as the quality of teachers. President Obama's campaign quickly responded with a video featuring a former Massachusetts school superintendent attacking the cuts and a fifth-grade teacher saying, "Come be in a classroom with fifth graders and tell me class size doesn't matter." Education - mainly given lip service in the national campaign - received detailed attention as Mr. Romney and Mr. Obama wedged in appearances at an education forum on Tuesday around more high-profile speeches in New York City on foreign affairs. Mr. Romney also attacked teachers' unions for opposing merit pay tied to testing and for supporting Democrats who negotiate contracts with them. He criticized the role of Mayor Rahm Emanuel, Mr. Obama's former chief of staff, who negotiated with the teachers' union in the recently ended Chicago strike. "I don't mean to be terribly partisan, but I kind of am," Mr. Romney said at the forum, Education Nation, sponsored by NBC News, drawing laughs. In July, Mr. Romney laid out a detailed agenda for education, including vouchers and restoring private banks to the subsidized college-loan market, but he rarely mentions these on the campaign trail, preferring to speak in generalities. Before an audience of educators and policy mavens, however, he returned to specifics, including his support for A-to-F grades for public schools and for transforming $25 billion in federal aid to schools into a program of vouchers for poor and disabled students. Mr. Obama, who spoke in a taped interview, accused Mr. Romney and his running mate, Representative Paul D. Ryan of Wisconsin, of teacher-bashing and of favoring deep cuts in government aid to education. "They talk a good game about reform, but when you actually look at their budgets, they are talking about slashing our investment in education by 20 percent, 25 percent," Mr. Obama said. Behind the debate over class size, school choice and other education issues is a traditional left-right fight over public spending, although these days many Democratic reformers, including the president, have embraced parts of the Republican agenda. Research from the 1980s showed students in early grades in classes of 13 to 17 performed significantly better than students in classes of 22 to 25. Many states passed laws limiting class size. But since then some economists have argued that an effective teacher has more of an impact on learning. One Democrat who has expressed support for the cost-effectiveness argument is Arne Duncan, Mr. Obama's secretary of education. Mr. Romney praised Mr. Duncan at Education Nation, but he dodged a question about whether he would reappoint him in a Romney administration.