President Donald Trump pushed U.S. Postal Service officials to double package delivery rates paid by Inc. and other companies, the Washington Post reported, highlighting that his beef with the e-commerce giant and founder Jeff Bezos go beyond tweets.

Trump pressured U.S. Postmaster General Megan Brennan to raise Amazon’s rates, which Brennan resisted by explaining that the agency was bound by contract and any changes would have to be approved by a regulatory commission, the newspaper said, citing unidentified people familiar with their conversations.

Amazon shares slipped 0.3 percent to $1,576.65 in afternoon trading in New York. That’s roughly where they were before the report. The White House declined to comment and the Postal Service didn’t immediately respond to a request for comment on Friday.

Trump recently ordered a review of the Postal Service’s finances and suggested on Twitter that…