"We're not placing an order," Whitehurst said. "It's in the assessment phase."
Whitehurst did not give specific numbers but said the order would be for "well over 100" new planes.
"Obviously, it would be a massive order when we make that decision," he said.
Whitehurst spoke with The Associated Press after The Wall Street Journal reported Whitehurst told the newspaper Delta may order as many as 125 of Boeing's 787 Dreamliners by the end of the year.
Whitehurst told the Journal the order is still being negotiated while Delta considers seat configurations and how much the planes would cost to operate and maintain.
The move to replace its fleet of 104 767s comes as Delta looks to expand its international service.
Since emerging from bankruptcy on April 30, the airline has outlined plans to cut domestic capacity and increase internationally.
The 787 Dreamliner, the first commercial jet made of light, sturdy, carbon-fiber composites instead of aluminum, has been a big seller for Chicago-based Boeing. Heading into the weeklong Paris Air Show, Boeing had already pocketed 584 orders for the Dreamliner, compared with Airbus' total of 13 firm orders and 142 non-final commitments for its A350.
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