NEW YORK (AP) — President Barack Obama and former President Bill Clinton are promoting the nation’s new health care law in advance of a critical sign up period.

The joint appearance is a rare conversation between two political figures who were once campaign trail foes but who have joined forces behind a common goal.

Clinton is playing the role of interviewer, prodding Obama to tout the law’s benefits and its connection to the economy. Obama says Americans are scared by the prospect of change but that he’s confident they will be swayed by its advantages.

The event comes one week before people who don’t have health insurance can start signing up at new insurance marketplaces. It also comes 20 years after Clinton called on a joint session of Congress to overhaul the nation’s health care.