Amazon founder Jeff Bezos speaks during a meeting with President-elect Donald Trump and technology industry leaders at Trump Tower in New York, Wednesday, Dec. 14, 2016.

The U.S. Postal Service has proposed a 9 to 12 percent increase in fees for the shipping service used by Amazon, just months after President Donald Trump criticized the USPS, saying it gives Amazon too good of a deal.

The parcel select service, which is also used by United Parcel Service and FedEx, is the last and typically the most expensive step in the shipping process that gets the packages to customers' doorsteps. The USPS proposed a 9.3 percent increase on this service for packages weighing over one pound and a 12.3 percent increase on lighter packages.

Trump issued an executive order in April to set up a task force to examine the USPS, claiming that it was on an "unsustainable financial path." He's also tweeted that the USPS is Amazon's "delivery boy" and doesn't make money from Amazon's business.

Trump tweet

A USPS spokesperson said these proposed changes are not a response to Trump's criticism.

"The price increases reflect the best judgment of the Postal Service Governors, who are seeking to establish new rates that will keep the Postal Service competitive, while also providing the Postal Service with much needed revenue," the spokesperson said.

The USPS also proposed a 3.9 percent increase on priority mail express, a 5.9 percent increase on priority mail and a 10 percent increase on first-class stamps.

These changes, if approved by regulators, will go into effect on Jan. 27, 2019.

WATCH: Trump blasts Amazon, calls for US Post Office to raise prices