Rex Tillerson's disclosure that he stands to receive a $180 million cash payout from Exxon Mobil Corp. if he becomes the next U.S. secretary of state offers a preview of the thorny ethical questions that may be raised this week over a presidential Cabinet stacked with wealthy tycoons.

And with confirmation hearings scheduled for Tillerson and eight other appointees of President-elect Donald Trump, the head of the federal office that helps ensure compliance with conflict-of-interest rules told lawmakers his agency is hard-pressed by too much work and too little time.

Tillerson ironed out an agreement with the State Department under which Exxon would pay the cash into an independent trust for him, a move designed to separate his financial interests from the oil company that he led as chairman and CEO until he stepped down Jan. 1. Some compensation specialists question whether Exxon departed from its official compensation policies to extend its former leader a special arrangement; the company says it hasn't.