WASHINGTON (AP) — Under sharp criticism from senators, a Facebook executive on Tuesday defended the social network's ambitious plan to create a digital currency and pledged to work with regulators to achieve a system that protects the privacy of users' data.

"We know we need to take the time to get this right," David Marcus, the Facebook executive leading the project, told the Senate Banking Committee at a hearing.

But that message did little to assure senators. Members of both parties demanded to know why a company with massive market power and a track record of scandals should be trusted wit...