Obama Begins Campaign Tour of Ohio and Pennsylvania SANDUSKY, Ohio - President Obama, betting that the glimmers of a resurgence in the Rust Belt could lift him to victory in the fall, set off Thursday on a two-day bus tour of Ohio and Pennsylvania, promoting himself as a defender of American manufacturing jobs and taking aim at those he said could steal those jobs away. One of the culprits, Mr. Obama said, is China. Speaking to a happy, if overheated, crowd outside Toledo, he announced that the United States would file a complaint with the World Trade Organization against China for duties imposed on American-made cars and trucks, including the Jeep Wrangler, which is built at an Ohio factory. "As long as we're competing on a fair playing field instead of an unfair playing field, we'll do just fine," Mr. Obama declared, standing before a red barn draped with bunting and a large American flag. But we're going to make sure competition is fair. It was a day of sweaty handshakes and fast-melting ice cream cones, as Mr. Obama's armored black bus snaked across northern Ohio, its hulking profile blurry in the shimmering heat waves. In one-on-one encounters at a farm market and a diner, and in a speech at an ice cream social, Mr. Obama sought to sharpen his message on the economy, etching the differences between him and his Republican challenger, Mitt Romney. The tour gives Mr. Obama the chance to make an argument that however weak the job market is nationally, the outlook for battleground states like Ohio is brightening. With the release of another potentially poor employment number on Friday, that argument could allow him to weather the ebbs and flows of a fragile economy. Mr. Obama has used the bailout of the auto industry as a calling card in the industrial Midwest, particularly in Ohio, and his announcement of trade action against China played to a constituency that is already favorably disposed to him. He reminded the audience, "Governor Romney said we should just let Detroit go bankrupt." "Governor Romney's experience has been in owning companies that were called "pioneers in outsourcing," " Mr. Obama said, referring to reports that firms controlled by Bain Capital moved jobs overseas. Our experience has been in saving the American auto industry. And as long as I'm president, that's what I'm going to be doing. Mr. Romney's campaign quickly fired back, saying that the president was engaging in "false and discredited attacks in an attempt to distract voters from his failed economic record." With Mr. Romney vacationing for the week with his family in New Hampshire, the campaign dispatched two surrogates to Ohio, former Gov. Tim Pawlenty of Minnesota and Gov. Bobby Jindal of Louisiana, to counter the president's message. "Of course we should bet on America," said Mr. Pawlenty, a potential running mate for Mr. Romney, in a local radio interview. But we shouldn't double down on Barack Obama. His presidency has been a losing hand for Ohio. Ohio's unemployment rate was 7.3 percent in May while Pennsylvania's was 7.4, both lower than the national average of 8.2 percent. Political analysts caution that the national unemployment rate - and the perception of the overall economy - tends to drive the decisions of voters more than state-by-state statistics. Still, the Midwest is benefiting from a modest recovery in manufacturing, the lack of a housing bubble that sapped the economy in other parts of the country, and the development of new industries like hydraulic fracturing, or fracking. In a recent statewide survey by Quinnipiac University, Mr. Obama was leading Mr. Romney in Ohio by 47 percent to 38 percent - his largest lead, where earlier polls showed a close race. The administration said this was the seventh such action it has taken against China - including its 2009 move against China for dumping tires in the American market - a pace that is double that of the Bush administration. In his first foray outside Washington since the Supreme Court upheld his health care law last week, Mr. Obama also offered a robust defense of the law, saying that Americans did not want to refight the battles of two years ago. "I'll work with anybody who wants to work with me to continue to improve our health care system and our health care laws," he said to cheers. But the law I passed is here to stay. It is going to make the vast majority of Americans more secure. After his speech here, Mr. Obama consoled a woman, Stephanie Miller, who told him that her sister died of cancer four years ago. The sister, Ms. Miller said later in a telephone interview, had not been able to afford health insurance, having been told that she earned too much to qualify for Medicaid. The Obama campaign is calling this tour, which will wind from outside Toledo to near Cleveland and on Friday to Pittsburgh, the "Betting on America" tour. The president made time for stops at the Kozy Corners diner in Oak Harbor and the Bergman Orchards farm market near Lake Erie, where he bought peaches and a dozen ears of corn. At the diner, Mr. Obama spent time talking to an emergency-room nurse, Kim Wein. "Let me tell you, first of all, I love nurses," the president said to her. Getting money from Congress to pay for more nurses and emergency workers was part of Mr. Obama's $447 billion jobs bill. The lunchtime crowd of 75 or so customers gave Mr. Obama a warm welcome as he sat down to a cheeseburger and fries. But one woman, Traci Riechman, said she was not sure it would translate to a winning margin for the president in November. "We have a lot of houses for sale," said Ms. Riechman, who works for the Ottawa County Juvenile Court. It's just a tough time here in Oak Harbor. I don't know if the community will be positive or negative.