WASHINGTON (AP) – Democratic presidential candidate Bernie Sanders is threatening a floor fight over rules and platform planks at the party’s summer convention if the Democratic National Committee stacks the committees with supporters of Hillary Clinton.

Sanders writes in a letter to Democratic National Committee chair Debbie Wasserman Schultz that the makeup of the standing committees should reflect the level of support that he and Clinton received in the primaries and caucuses.

He says many of his supporters have not been included and notes Connecticut Gov. Dannel Malloy will be in charge of the convention’s platform committee and former Massachusetts Rep. Barney Frank will run the rules committee. He calls both “aggressive attack surrogates” for Clinton.

Sanders says if the process is unfair, he’ll challenge platform planks, electoral reform planks and rules changes.