United Airlines Holdings Inc. is in late-stage talks with Boeing Co. and Airbus SE as the carrier mulls narrow- and widebody models for potential blockbuster orders to bolster its fleet.

The Chicago-based airline is looking at taking more than 100 Boeing 787 Dreamliners as part of a “triple-digit” twin-aisle order that CEO Scott Kirby has touted to pilots, according to people familiar with the matter. The deal could include a mix of firm orders and commitments. The initial portion is expected to be unveiled within weeks, though the final terms and timing are in flux, one of the people said.

United also may convert an earlier order for Airbus’s A350 widebody jets to its longest narrowbody model, the A321neo, said the people, who asked not to be identified discussing confidential information. One potential snag to those talks: the lack of near-term delivery slots for the popular plane, which is largely sold-out through 2028.

Representatives of United, Boeing and Airbus declined to comment.

The potential multibillion-dollar deals would cap a monthslong process as United worked to wrap up talks with Boeing and Airbus before year-end, Bloomberg News reported in October. The Wall Street Journal reported Friday that United was nearing a deal to order dozens of Dreamliners, sending Boeing’s shares up 4%.

United has about 128 twin-aisle Boeing jets that are at least two decades old on average, according to Cirium data, an age where maintenance costs soar. The carrier likes the commonality of its current all-Boeing widebody fleet, a big consideration in its deliberations. The company has repeatedly postponed a deal for 45 Airbus A350 aircraft over the past decade.

The airline is expected to load up on Boeing’s smallest Dreamliner model, the 787-8, as a replacement for its 767 fleet, one of the people said. United has 54 of the aging midrange airliners, according to a Jefferies report.