DALLAS — The president of the pilots' union at American Airlines resigned Thursday after pilots rejected a concessionary contract offer that he supported.

David Bates said that the union's board asked him to step down, and he agreed.

Bates supported ratification of a company offer to give pilots pay raises and a 13.5 percent stake in the company after it emerges from bankruptcy protection. He portrayed it as the best deal possible under difficult circumstances. But 61 percent of pilots voted to reject the offer, which contained outsourcing provisions they opposed.

American said that a federal bankruptcy judge will rule next Wednesday on the airline's request to impose terms of an April offer that included smaller pay raises and no stock in the new company for pilots. The judge will delay a similar ruling for flight attendants, who are still voting through Aug. 19 on their offer from American.

American officials declined to comment.

The Allied Pilots Association board named New York-based pilot Keith Wilson, a veteran of the union's negotiating committee, as interim president for the rest of Bates' term, which runs through next June.