This undated handout image provided by the U.S. Postal Service shows the new “forever” stamps. The post office wants to increase the price of a stamp by 2 cents to 46 cents starting in January. The agency has been battered by massive losses and declining mail volume and faces a financial crisis.

Washington ? Buy those Forever stamps now. The cost of mailing a letter is going up again.

Fighting to survive a deepening financial crisis, the Postal Service said Tuesday it wants to increase the price of first-class stamps by 2 cents — to 46 cents — starting in January. Other postage costs would rise as well.

The agency’s persisting problem: ever-declining mail volume as people and businesses shift to the Internet and the declining economy reduces advertising mail.

“The Postal Service faces a serious risk of financial insolvency,” postal vice president Stephen M. Kearney said, an indication that without significant changes a time could come when the agency would be unable to pay its bills.

The post office lost $3.8 billion last year, despite cutting 40,000 full-time positions and making other reductions, and Kearney said it is facing a $7 billion loss for this year and the same for fiscal 2011, which begins in October. The rate increase would bring in $2.5 billion, meaning there still would be a large loss for next year.

The post office, though part of the government, does not receive a tax subsidy for its operations.

While the cost of a first-class stamp would go up, people who bought Forever stamps at the current 44 cents or at lower prices would still be able to use them without paying the difference.

Officials also said they plan a new design for Forever stamps, which currently have am image of the Liberty Bell. New Forever stamps will have images of evergreen trees. All Forever stamps would remain valid.

Under the proposed increases, in addition to the 46-cent rate for the first ounce, the cost for each additional ounce would go up a penny to 18 cents. The cost to mail a postcard would go up 2 cents to 30 cents.

The price to send periodicals would go up about 8 percent.