Story highlights President uses Labor Day speech to hammer Republicans

Wisconsin Gov. Scott Walker among those coming under fire

Boston (CNN) President Barack Obama lambasted Republican presidential candidates Monday, charging the GOP is treating American workers like a hostile force while looking out only for the rich.

Obama delivered a Labor Day speech in Boston, where he traveled to unveil a new executive order he signed forcing companies who contract with the federal government to provide paid sick leave to their employees.

Obama, saying he was relieved to not be on the ballot next November, hit at Republicans who he claimed were espousing policies that would erode the middle class.

"We're starting to hear a lot about middle-class values," he said. "Some folks seem confused about what exactly that means."

Without mentioning him by name, Obama struck at Wisconsin Gov. Scott Walker for answering a question about his ISIS strategy earlier this year by saying: "If I can take on 100,000 (union) protesters, I can do the same across the globe."

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