WASHINGTON — Peel it and weep: It'll cost an extra 2 cents to mail a letter starting Monday.

The price of a first-class stamp will climb to 44 cents.

It's the third year in a row rates have gone up in May under a new system that allows annual increases as long as they don't exceed the rate of inflation for the year before.

While the increase will bring in added income, the post office continues to struggle financially as more and more lucrative first-class mail is diverted to the Internet, and the recession discourages businesses from sending their usual volume of advertising.

The Postal Service, which does not get a taxpayer subsidy for its operations, lost $2.8 billion last year and is $2.3 billion in the hole just halfway through this year.

Postmaster General John Potter asked Congress for permission to reduce mail delivery to five days a week. The agency is offering early retirement to workers, consolidating excess capacity in mail processing and transportation networks, realigning carrier routes, halting construction of new facilities, freezing officer and executive salaries at 2008 pay levels, and reducing travel budgets.

While the new 44-cent rate covers the first ounce of first-class mail, the price for each additional ounce will remain unchanged at 17-cents.

The postcard stamp increases by a penny to 28 cents.