The New York Yankees and Pittsburgh Pirates have a framework in place for a possible A.J. Burnett deal and are working through conditions in that framework, baseball sources said Sunday.

The Yankees have been engaged in talks with four teams but the Pirates have emerged as the front-runner, sources said. Sources said that if a trade is agreed to the commissioner's office will have to approve the deal because of the large amount of money that will exchange hands.

One of the clubs was among teams Burnett can veto per his contract, a source said, and the right-hander was unwilling to give in on that team. It was uncertain what teams were in the bidding for Burnett beyond Pittsburgh.