Sen. Susan CollinsSusan CollinsA guide to the committees: Senate Pruitt sworn in as EPA chief Comey meets Intel senators amid uproar over Trump-Russia ties MORE (R-Maine) said she was “disappointed” in the U.S. Postal Service’s decision to increase prices and said the agency doesn’t have authority from Congress to make such a decision.

Last month, the Postal Regulatory Commission approved a rate increase on first-class, standard, periodicals and package mailing service. Collins said it could mean a 6 percent price increase.

“I am disappointed that the PRC has approved a postal rate increase averaging six percent,” Collins said. “My concern is that a rate increase of this magnitude will worsen the Postal Service's crisis by further driving down mail volume, eroding the Postal Service's steadily declining customer base, and leading to a further decline in revenues.”

USPS profits have greatly diminished as more people primarily use digital communication. Collins said USPS should be thinking of new services to provided rather than simply raising rates.

“The Postal Service should be implementing more initiatives that will increase volume and attract more consumers,” Collins said. “Even though temporary, these rate increases may well do just the opposite.”

Collins also questioned whether the rate increase is “contrary to law,” which ties price increases to inflation unless there are “extreme” circumstances.

“Congress intended the authority to increase rates under an exigent case to be used only in extreme and unforeseen instances — such as terrorist attacks, natural disasters, and other events,” Collins said. “The exigent rate provisions were not meant to be used to remedy poor economic performance or to offset an ongoing marketplace trend, such as the increased use of electronic mail."