The federal government and states are girding themselves for the next foreclosure crisis in the country’s housing downturn: payment option adjustable rate mortgages that are beginning to reset.

“Payment option ARMs are about to explode,” Iowa Attorney General Tom Miller said….”That’s the next round of potential foreclosures in our country,”…

Option-ARMs are now considered among the riskiest offered during the recent housing boom and have left many borrowers owing more than their homes are worth. These “underwater” mortgages have been a driving force behind rising defaults and mounting foreclosures.

In Arizona, 128,000 of those mortgages will reset over the the next year and many have started to adjust this month, the state’s attorney general, Terry Goddard, told Reuters after the meeting.

“It’s the other shoe,” he said. “I can’t say it’s waiting to drop. It’s dropping now.”