WASHINGTON — Saturday postal delivery could continue for at least two years, and the closing of post offices in smaller communities may not happen as quickly as advertised.

The Senate on Wednesday approved legislation that would slow the U.S. Postal Service’s effort to make such changes. By a 62-37 vote, it sent a strong bipartisan message that although the system is ailing financially, it’s not good politics, especially in an election year, to take a scythe to popular parts of the Postal Service.

“We don’t allow for what might be called shock therapy for the Postal Service because we don’t think it will work,” said Senate Homeland Security and Government Affairs Committee Chairman Joe Lieberman, a Connecticut independent and an architect of the bipartisan bill.

Not everyone agrees, and the plan still has to navigate a difficult road in the Republican-dominated House of Representatives. One proposal by key GOP lawmakers would set up a commission to devise a plan to consolidate and perhaps close certain post offices. The measure would give postal officials the option of ending Saturday service within six months of the bill’s enactment.

Many lawmakers in both chambers still see ending Saturday delivery as an important, timely and necessary cost-cutting move.

“It is clear the Postal Service must make drastic changes,” argued Sen. Bob Corker, R-Tenn.

The Postal Service has been struggling, battered by the 2007-09 economic recession and customers’ increasing reliance on electronic communication. First-class mail has dropped 25 percent in the last five years. Postal officials have proposed several strategies, including ending Saturday service and studying whether to close about 3,700 of the nation’s 31,509 post offices, and consolidate or close 234 of the 431 processing facilities. Many of the targeted post offices are in smaller, more rural areas, and lawmakers from affected states are howling.

Sen. Tom Udall, D-N.M., recalled meeting last week with residents of Mule Creek, N.M. They told him they have no cellphone service and no high-speed Internet.

“They depend on their post office,” he said. “It is the lifeline, the center of their community, and not just five days a week.”

But something has to be done to ease the Postal Service’s financial pain. The Government Accountability Office, Congress’ investigative arm, estimates that the Postal Service has lost $25 billion since 2006. Going to five-day-a-week delivery would save about $3.1 billion a year.

The Senate plan would bar the Postal Service from ending Saturday delivery for at least two years. Cutting five-day-a-week service would be the last option for saving money. If the Postal Service could not save money any other way — and the GAO agrees — Saturday service then could be ended.

Closing post offices still would be difficult, because the bill would require postal officials to work with local communities before closing a facility. Any closing could be appealed to the Postal Regulatory Commission, a five-member panel appointed by the president and subject to Senate confirmation.

The Senate bill, though, would save an estimated $19 billion by 2016, when it’s fully phased in. Among its changes: Overnight delivery would not be guaranteed unless sent to and from the same processing facilities. It would be easier for the Postal Service to end door-to-door service in limited instances and deliver instead to curbside or centralized facilities. It also would have two years to implement cost-saving changes, notably a workforce reduction of about 18 percent, or 100,000 jobs. They could be offered buyouts or retirement incentives.

In short, the politicians will be watching closely, and the message from the Senate was that they’re not sympathetic to radical changes.

“No matter how far we have come with technology in the digital age, there are some things that simply cannot be sent by email,” said Sen. Amy Klobuchar, D-Minn.