In what his campaign billed as his “closing argument,” Mitt Romney warned Americans that a second term for President Obama would have apocalyptic consequences for the economy in part because his own party would force a debt ceiling disaster.

“Unless we change course, we may well be looking at another recession,” Romney told a crowd in West Allis, Wisconsin.

Romney said that Obama “promised to be a post-partisan president, but he became the most partisan” and that his bitter relations with the House GOP could threaten the economy. As his chief example, he pointed to a crisis created entirely by his own party’s choice — Republican lawmakers’ ongoing threat to reject a debt ceiling increase. Economists warn that a failure to pass such a measure would haveimmediate and catastrophic consequences for the recovery.

“You know that if the President is re-elected, he will still be unable to work with the people in Congress,” Romney said. “He has ignored them, attacked them, blamed them. The debt ceiling will come up again, and shutdown and default will be threatened, chilling the economy.”

Despite the apocalyptic warnings on the economy, most of the Republican nominee’s speech focused on a more modest argument that as president he would work with both sides to build a stronger economy. He said that, like Obama, “I promise change, but I have a record of achieving it.”