AP October 10, 2018, 10:30 PM Postal service proposes price increase for stamps

NEW YORK – MAY 14: U.S. Postal Service spokeswoman Pat McGovern displays the U.S. Postal Service's new "forever" stamp booklet inside the James A. Farley post office building May 14, 2007 in New York City. The "forever" first-class stamps will remain valid regardless of price increases in the future. New postage prices went into effect today with the price to mail a first-class letter increasing to 41 cents. (Photo by Mario Tama/Getty Images)

Mario Tama, Getty Images

WASHINGTON — The U.S. Postal Service is seeking to increase the price of its first-class stamp by 5 cents to 55 cents to help stem its mounting red ink. If approved by regulators, the 10 percent increase to the cost of mailing a 1-ounce letter would be the biggest since 1991.

The price of each additional ounce would go down, from 21 cents to 15 cents.

The proposed increase would take effect in January. It comes as President Trump has criticized the Postal Service for "losing a fortune" by not charging higher shipping rates for online retailers such as Amazon.com.

The Postal Service has seen years of financial losses as an unrelenting drop in mail volume and costs of its health care and pension obligations outweighed strong gains in package deliveries.