ST. CLAIR SHORES, Michigan—Sen. Rick Santorum struck a sharper tone on the campaign trail today, criticizing Mitt Romney for questioning his conservative values and calling him an "Occupy Wall Street adherent."

"It’s absolutely laughable to have a liberal governor of Massachusetts say that I am not a conservative," Santorum said, attacking Romney's tax plan. “We have a candidate for president who is campaigning as an Occupy Wall Street adherent.”

"He doesn't understand how America works any more than Barack Obama understands how America works," Santorum said, about Romney's plan to cap wealthy individuals' ability to deduct charitable contributions.

He contrasted his record with Romney, "who created the biggest entitlement program in Massachusetts and gave us Obamacare.”

Santorum repeating his charge that Romney and Ron Paul are working together to attack him, saying "the coordination that I felt at that debate that night was pretty clear — it was like they were passing messages behind my chair."

Santorum then unloaded on Paul, responding to his charge on Wednesday night that he is 'a fake.' "Let’s see who’s calling who a fake," Santorum said. "His conservative rating has been one of the worst in Congress. His conservative rating is as bad as some liberal democrats, maybe it’s for different reasons. He’s no conservative."

Santorum also attacked President Obama's energy policy, accusing him of systematically raising energy prices to prevent global warming, a science Santorum said he considered political science.

“I don’t understand how you wake up in the morning when you consistently mislead,” Santorum said of Obama. "This president will not take responsibility for anything that goes on in his administration."