A group of some of bankrupt American Airlines' most significant bondholders said that it will not support a standalone restructuring unless a new board is brought in, a move that may increase hurdles for Chief Executive Tom Horton and his team, Reuters reported today. The 12-member bondholder group, which includes JPMorgan Chase & Co, Pentwater Capital Management and York Capital Management, is the primary group to have expressed an interest in funding an independent exit for the airline's parent company AMR Corp. AMR's current management team, led by Horton who is also chairman of the board, has lost the confidence of the company's unions, which support a takeover bid by smaller competitor US Airways Group. The bondholders, who hold more than $700 million in AMR debt, said in the letter to Keith Wilson, president of American's pilots' union, that its support for an independent exit was "conditioned, among other things, on that plan providing for the naming of a new board of directors."