Amazon.com Inc and other retail and logistics companies said on Wednesday they had started a new group to lobby to keep the U.S. Postal Service's package delivery services "reliable and affordable."

The announcement follows a string of attacks on Amazon by President Donald Trump, complaining that the world's largest e-commerce company does not pay the U.S. Postal Service a fair rate for package delivery.

Trump has said, without citing evidence, that this costs U.S. taxpayers billions of dollars, and he has threatened to raise its postal rates.

The Package Coalition made no reference to Trump in a statement announcing its formation, but said it wanted to work with policymakers and the public to highlight the importance of the postal service to homes and businesses.

"Reliable and affordable postal package delivery is a key engine of the American economy," said John McHugh, the coalition chairman. McHugh, a former member of Congress, served as chairman of the government's Postal Service subcommittee.

Members of the new group include Columbia Sportswear , pharmacy benefits manager Express Scripts , the National Retail Federation, package shipping firm OSM Worldwide, postal service company Pitney Bowes , Publishers Clearing House and the retailer QVC.

Members of the group pay the Postal Service to deliver goods the last mile to more than 150 million U.S. homes and businesses, the coalition said.

"Without (the Postal Service), consumers would have fewer shipping options, reduced service in rural areas, and prices would drastically increase," said Blair Anderson, director of transportation policy at Amazon.

The company did not answer a request for further comment beyond the Postal Coalition statement.