UPDATE 1-Chicago Mercantile, CBOT Holdings set July 9 for vote

(Recasts, updates with details of merger battle)

NEW YORK, April 11 (Reuters) - Prospective merger partners Chicago Mercantile Exchange Holdings Inc. CME.N and CBOT Holdings Inc. BOT.N rescheduled their postponed shareholders' meetings to vote on the deal to July 9, as a rival bid for CBOT remains on the table.

The two exchanges said the rescheduled date would give CBOT time to complete its evaluation of the unsolicited proposal by the IntercontinentalExchange Inc. (ICE.N), which is also bidding for CBOT.

The meeting to approve the deal between the No. 1 and No. 2 futures exchanges had originally been scheduled for April 4.

"While we continue to move forward with our existing agreement with the CME, as we are required to do, we also continue to ... carefully evaluate ICE's proposal," said Charles Carey, chairman of the boards of CBOT Holdings and the CBOT in a statement.

CBOT said it would have no further comment until its boards completed their review of the proposal.

ICE, a small Atlanta-based energy exchange with a clearing house at the New York Board of Trade, in March offered almost $10 billion to acquire the CBOT.

That bid bested CME's, which was made in October, by more than $1 billion.

"We continue to believe that the combination of CME and CBOT provides unparalleled growth potential," said CME Executive Chairman Terry Duffy in a statement. "We look forward to putting the vote before our shareholders and proceeding with our merger."