Mitt Romney accused President Barack Obama of siding with striking unionized teachers in Chicago at the expense of students, a charge the White House dismissed. \"President Obama has chosen his side in this fight, sending his vice president last year to assure the nation\'s largest teachers union that \'you should have no doubt about my affection for you and the president\'s commitment to you,\'\" the Republican presidential nominee said in a statement issued by his campaign as he flew to an Ohio campaign event. Vice President Joe Biden addressed the 3.2 million-member National Education Association\'s annual convention in Chicago July 3, 2011. Biden told the estimated 9,000 attendees, \"One thing you should not have any doubt in your mind about is that Barack Obama, he is on your side. Make no mistake about it.\" But he also said \"not all teachers are created equal\" and educators had an \"obligation\" to show accountability so their profession can be \"the best, the most competent and capable it can be.\" Romney statement said that in contrast to the Obama administration, \"I choose to side with the parents and students depending on public schools to give them the skills to succeed, and my plan for education reform will do exactly that.\" White House spokesman Jay Carney responded to Romney, saying Obama had \"not expressed any opinion\" about the strike, but \"his principal concern is for the students and families who are affected by the situation.\" \"We hope that both sides are able to come together to settle this quickly and in the best interest of Chicago\'s students,\" Carney said. Obama and Education Secretary Arne Duncan, a former Chicago schools chief, have advocated policies, such as school choice and using tests in teacher evaluations, that teachers unions don\'t generally like. But the administration has also used stimulus money to pay for teacher salaries, winning union support. Obama \"believes, as he says frequently, that investing in education now pays enormous economic dividends later,\" Carney said Monday. Romney\'s statement said, \"Teachers unions have too often made plain that their interests conflict with those of our children, and today we are seeing one of the clearest examples yet\" in the Chicago strike. Rahm Emanuel, mayor of Obama\'s adopted hometown of Chicago and formerly Obama\'s chief of staff, told reporters he appreciated Romney\'s \"lip service,\" but said \"what really counts is what we are doing here.\" \"I don\'t give two hoots about national comments scoring political points or trying to embarrass -- or whatever -- the president,\" he said. About 23,000 public school teachers plus support staff marched in red T-shirts outside empty schools Monday while about 400,000 children were left with nothing to do. Tuesday promised to be a repeat. The union in the third-largest U.S. school district is striking over failure to reach agreement on several issues, including teacher evaluations, hiring, healthcare and salary. The two sides say they\'re close in salary negotiations, but apart on other issues, such as health-insurance changes and evaluation systems that rank teachers partly based on students\' standardized tests scores.