UPS United Parcel Service

By Peter Nicholas and Laura Stevens 

WASHINGTON -- President Donald Trump stepped up his attacks on Amazon.com Inc. on Tuesday, sending out a tweet saying that the company is a drain on the U.S. Postal Service, using the mail system as a "delivery boy."

Amazon, he wrote, "should pay these costs (plus) and not have them bourne [sic] by the American taxpayer."

The morning tweet is the fifth in five days Mr. Trump has aimed at Amazon, whose stock has been buffeted by the president's focus.

In his latest tweet, Mr. Trump also targeted the Postal Service over what he said are the multibillion-dollar losses stemming from Amazon deliveries.

"P.O. leaders don't have a clue (or do they?)!" he wrote.

In his tweets, Mr. Trump has invoked many of the same themes: Amazon profits at the expense of the Postal Service and other retailers suffer because of Amazon's enviable market position.

He has also spotlighted the ties between Amazon and the Washington Post. Jeff Bezos, chief executive of the company also owns the Washington Post.

In tweets over the past year he has complained repeatedly about the newspaper's coverage while also suggesting without evidence the Post is a "lobbyist" for Amazon.

An Amazon spokeswoman declined to comment. The U.S. Postal Service didn't immediately respond to a request for comment.

In remarks Monday, Washington Post Executive Editor Martin Baron said the newspaper operates independently from Amazon and that Mr. Bezos hasn't meddled in the Post's news coverage.

"I can't say more emphatically he's never suggested a story to anybody here, he's never critiqued a story, he's never suppressed a story," Mr. Baron said in an interview with the New York Times.

Amazon's stock price has taken a hit over the past week, hurt by a broader stock-market slump and a news report regarding Mr. Trump's anger with Amazon on Wednesday. Since the market's close a week ago, the company's stock price has fallen 8% as of Tuesday morning trading.

While the U.S. Postal Service does lose billions of dollars annually, much of that is attributable to an unusual requirement it prefund many of its pension liabilities. The service has also been hard hit by a decline in first-class mail, one of its most profitable products.

Amazon primarily uses the Postal Service for so-called last mile delivery, where they sort and drop off packages at the local post office and the letter carrier brings those to the door. United Parcel Service Inc., FedEx Corp. and a few other companies have similar agreements with the quasigovernmental agency.

The package business has helped bolster the Postal Service's financial strength, according to officials, and the Postal Service is mandated by Congress to charge enough to cover its costs. But some critics have said officials have priced this type of delivery option too low, effectively cross subsidizing package delivery with its mandate to delivery mail to U.S. addresses.

White House aides have debated internally what could be driving the president's criticism of Amazon, with theories including the Washington Post's coverage of the administration and the effect the company has had on Trump associates' businesses, according to an administration official.

While the motivation remains unclear, aides have noted that the president's tweets on the subject have put the White House on the offensive, rather than defending itself against stories including allegations by former adult-film star Stormy Daniels and other women.

--Rebecca Ballhaus contributed to this article.

Write to Peter Nicholas at peter.nicholas@wsj.com and Laura Stevens at laura.stevens@wsj.com

(END) Dow Jones Newswires

April 03, 2018 13:20 ET (17:20 GMT)

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