WASHINGTON -- California high-speed rail officials allied themselves with Amtrak on Thursday, forming a politically attuned partnership designed to ease the purchase of similar trains.

In a new effort to wed West Coast and East Coast transportation interests, officials will formally request information from manufacturers about their ability to build "train sets" that can service different regional needs. A train set consists of a number of cars linked together, one of a rail system's many expensive requirements on which planners hope to save money.

"The potential is there, if we can come up with a common set of specifications," Jeff Morales, the chief executive officer of the California High-Speed Rail Authority, told reporters gathered in Union Station. "It's like going to Costco: If you buy it in bulk, you can lower your price."

California plans to initially buy 27 high-speed rail train sets, for a system that's supposed to start running by 2022. Officials anticipate breaking ground in Fresno this summer on the first 130-mile segment, connecting Bakersfield and Merced.

Separately, Amtrak is planning to buy about 32 high-speed train sets to serve the Northeast Corridor, connecting Washington and Boston via New York.

Train sets can cost anywhere from $35 million to $55 million each, Joe Boardman, Amtrak's president and chief executive officer, estimated Thursday. Unlike conventional trains, on which locomotives propel inert passenger cars, the new trains proposed for use by Amtrak and California would have power distributed through each car.

Rail-wise, the regions have differences and similarities.

Amtrak officials need trains that start with high speeds of about 150 mph and could move faster eventually as tracks are improved. California officials anticipate a system in which trains will travel at up to 220 mph.

Along the urban Northeast Corridor, Amtrak officials need a train whose undercarriage can handle a lot of curves and complications. California officials, whose proposed route shoots like an arrow through the rural San Joaquin Valley, don't need that. Amtrak wants train sets that can seat 400 to 600 passengers, while California seeks smaller packages carrying 450 to 500 passengers.

"Our common goal here is to drive toward as much uniformity as possible," Morales said.

The kickoff of the rail alliance Thursday is supposed to lead to a formal request for proposals from manufacturers by September, with manufacturing orders for the train sets placed next year.

"California is with us on this," Boardman said, adding that "this is a way to bring high-speed transportation to the United States."

The rail announcement occurred a day after high-speed rail skeptic Rep. Jeff Denham, R-Turlock, was elevated to the chairmanship of the House of Representatives rail subcommittee. Morales and Dan Richard, the chair of the California High-Speed Rail Authority, met with Denham on Wednesday morning. The meeting might be one of many to come, as Denham and other Republican lawmakers press California officials on everything from estimates to ridership projections.

"He has questions, and he has concerns," Morales said Thursday, "and it's our responsibility to answer those questions and address his concerns."