The U.S. Postal Service (USPS) announced Wednesday that it will discontinue mail delivery on Saturday, while continuing to distribute packages six days a week.

Postmaster General Patrick Donahoe told reporters that the switch, which would go into effect in August, is the cash-strapped agency’s latest step to adapt to how customers use the mail in an increasingly digital world.

Ending Saturday delivery, Donahoe said, would save roughly $2 billion a year, and the postmaster general cited polling asserting that the public would back the move.

USPS would continue delivering to post office boxes on Saturday, and local branches with Saturday hours would continue to stay open. The move comes as USPS has seen declines in the use of first-class mail, but a boost in its package shipping.

“We cannot put our head in the sand and say, ‘Well, jeez, let’s hope this problem goes away,’ ” Donahoe said at a news conference. “Hope is not a strategy.”

The USPS announcement is something of a shift for the agency, which had previously pleaded with Congress to give it the authority to scrap Saturday delivery.

Lawmakers were unable to reach a bipartisan deal to overhaul the Postal Service during the last Congress, even though the Senate passed a measure in April 2012. House GOP leaders never brought their preferred bill to the floor last Congress.

At the same time, Congress continued to approve language in appropriations bills, as it has for roughly three decades, mandating six-day delivery.

But Donahoe said Wednesday that USPS thought it could make the switch, in part because the agency does not get funding for future operations through government spending bills.

In any case, Donahoe said he hoped to work with lawmakers over the next six weeks to ensure that language on delivery standards was left out of the next government funding measure. The current continuing resolution expires on March 27.

“We have no interest in trying to catch Congress in a loophole. That’s not our interest,” Donahoe said. “We want to work with Congress to do the right things. We think right now the opportunity exists.”

Top Republicans working on postal issues supported the USPS, and said they would work to keep six-day language out of the next government spending bill.

“The Postal Service faces an uncertain future as it struggles to cope with the diminishing demand for paper-based communication,” Rep. Darrell Issa (Calif.), the chairman of the House Oversight Committee, and Sen. Tom CoburnThomas (Tom) Allen CoburnThe Hill's Morning Report — Presented by PhRMA — Worries grow about political violence as midterms approach President Trump’s war on federal waste American patients face too many hurdles in regard to health-care access MORE (Okla.), the ranking Republican at the Homeland Security panel, wrote to congressional leaders.

Still, the USPS announcement did spark some criticism – some of it sharp – from both Democrats and postal unions.

Some Democrats have long said that ending Saturday delivery would eat into USPS’s ability to compete with the private sector, and have said the biggest factor in the agency’s funding issues is its requirement to prefund future retiree healthcare.

Around 70 percent of the Postal Service’s record losses in 2012 – $11.1 billion out of $15.9 billion – stemmed from defaults on those required prepayments.

Sen. Tom CarperThomas (Tom) Richard CarperOvernight Defense: House passes T spending package with defense funds | Senate set to vote on blocking Saudi arms sales | UN nominee defends climate change record Overnight Defense: House passes T spending package with defense funds | Senate set to vote on blocking Saudi arms sales | UN nominee defends climate change record Bipartisan senators propose forcing EPA to set drinking water standard for 'forever chemicals' MORE (D-Del.), the chairman of the Senate Homeland Security Committee, and Rep. Elijah Cummings (Md.), the top Democrat on the House Oversight Committee, both said Wednesday that they were disappointed that the USPS would circumvent Congress in moving to five-day delivery.

“Despite my disappointment, it’s hard to condemn the postmaster general for moving aggressively to do what he believes he can and must do to keep the lights on at the Postal Service, which may be only months away from insolvency,” Carper said in a statement.

Postal unions responded much more sharply. Fredric Rolando, the president of the National Association of Letter Carriers, called for Donahoe to be removed as postmaster general, while Jeanette Dwyer, of the National Rural Letter Carriers, termed the move “yet another death knell.”

At the Capitol on Wednesday, Speaker John BoehnerJohn Andrew BoehnerTed Cruz, AOC have it right on banning former members of Congress from becoming lobbyists Ted Cruz, AOC have it right on banning former members of Congress from becoming lobbyists Rep. Amash stokes talk of campaign against Trump MORE (R-Ohio) said he hoped Congress would act “soon” on a broader postal reform measure, and said lawmakers had tied the agency’s hands for years.

White House press secretary Jay Carney, meanwhile, said that the administration had been informed of the Postal Service's decision just a day before.

Carney said that it was the White House's "preference" that Congress take up a series of postal reforms suggested by the president during his first term. The administration has previously supported allowing the USPS to scrap six-day delivery.

This story was first posted at 7:59 a.m. and has been updated.