"I have stated my concerns with Amazon long before the Election", Trump tweeted Thursday.
Trump also wants to change Amazon's tax treatment, the report said, an issue the president raised publicly a year ago when he called for an internet tax for online retailers, even though Amazon already collects sales tax on items it sells direct to customers. Toys R Us and other retailers that have filed for bankruptcy or gone out of business have said that Amazon's low prices were hard to compete with. However, Amazon and other big e-commerce companies now routinely collect state sales taxes.
Trump's tweet comes a day after news site Axios reported that he "hates" Amazon and has talked about changing Amazons tax treatment because he was "worried" about mom-and-pop retailers being put out of business.
The U.S. Postal Service has been roiled by the same gale-force technology winds, as Americans abandoned mail for email and other electronic communication. It is well known that there is a personal feud between Trump and Amazon founder Jeff Bezos, who now also owns The Washington Post.
"Amazon doesn't collect sales taxes on goods sold by third-party affiliates, unless it is contracted to do so by those sellers", the official said.
Stifel analyst Scott Devitt said the e-retailer collects sales taxes in the 45 states that have state sales taxes and the District of Columbia.
The issue is still being disputed at the federal level, with the US Supreme Court set to hear oral arguments on April 17 in a case which could reverse a 1992 decision that only companies with a physical presence in a state are required to collect state sales tax. Separate figures in the report show it was expecting to pay $100 million to $200 million in taxes at the USA state level in 2017. Not only is Amazon a highly innovative company, but it helps other companies be productive - especially third-party resellers.
"Common sense suggests USPS needs Amazon more than Amazon needs USPS", Stifel analysts wrote in a research report this week. Soon after Trump's tweet, the White House indicated imposing taxes on such companies. The US president pointed out that Amazon does not pay enough taxes, hurts traders, and receives an unfair advantage at the back of the US Post Office.
In July a year ago, Donald Trump tweeted that many articles about him in the Post were "fake news" and in another tweet he asked if the Washington Post was being used as a "lobbyist weapon" against Congress.
Sources say Amazon had cut ties from the lobbying firms last Friday and in their place hired Paul Brathwaite of Federal Street Strategies LLC and Josh Holly of Holly Strategies Inc, both of whom have previously worked as outside lobbyists for Airbnb Inc and Oracle.
The Postal Service declined to comment on Trump's tweet.
The Postal Service could charge Amazon higher rates, but first, Trump would need more appointees on the Postal Regulatory Commission, which lacks a quorum.
To comply with federal law, the Postal Service in 2017 had to generate at least $1.6 billion in income from its "competitive nonpostal services", which includes Amazon package deliveries.
Amazon has undoubtedly contributed to the closure of many brick-and-mortar stores and the bankruptcy of some chains as more people shop online instead of in malls.
In another financial report a year ago, USPS said growth in its package business was "a result of our successful efforts to compete in the ground shipping services and "last mile" e-commerce fulfillment markets, including Sunday delivery".