Having a post office nearby is serious business for residents of Leisure World, a 610-acre, private senior citizen community in Silver Spring, Md.

“You have to be at least 55 to live in the community,” said Barbara Cronin, chairwoman of the board that helps govern the community. “Seniors who moved here 20 years ago aren’t as active as they used to be.”

So when the post office at Leisure World Plaza — located just outside the complex and serviced by Leisure World buses — was put on the chopping block by the U.S. Postal Service, residents contacted Rep. Chris Van Hollen (D-Md.). And on Feb. 9, he announced via press release that he had managed to stave off its closure.

“The closest post office is a few miles away in [Aspen Hill, Md.], but that would be difficult to get to if you don’t drive,” Cronin said. “It becomes a real-world issue.”

The Leisure World Plaza post office and others around the nation are not out of the woods yet as the Senate debates a bill this week to reform the USPS. The Postal Service has struggled financially in recent years as more people rely on paperless, electronic communications. The USPS — which is the second largest civilian employer after Walmart, with about 570,000 employees — projects a $14.1 billion net loss for fiscal 2012.

But the plan to close post offices around the country has run into some serious roadblocks. Lawmakers have sprung into action to help save their mail facilities, an important constituent service. And in Van Hollen’s case, those constituents included Leisure World’s 8,500 senior citizens, who are among the most reliable voting demographic in the country.

“We need to look at the post offices and how they are being used,” Van Hollen said. “Communities are in a good position to know how used their post offices are, and anyone who knows Leisure World in my district, knows that you have a senior population that does use postal services; they are still writing a lot of letters, so they rely on that post office.”

Sen. Barbara Mikulski (D-Md.) was more blunt: “This is ZIP code politics.” She is fighting to keep a mail-processing center open — and retain the jobs it provides — in Easton, Md., as part of the Senate debate this week.

But Sen. John McCain (R-Ariz.) said he sees the efforts of Members to save their post offices as similar to when lawmakers oppose the closures of military bases.

“There are powerful forces lobbying against it,” said McCain, who opposes the Senate legislation. “This bill would be just a Band-Aid, not a fix.”

He supports a House GOP measure and has introduced the companion in the Senate.

The Postal Service is “a victim of technology, just as the Pony Express was victim of technology when the railroads came in,” McCain said. “That is what it’s all about. The question is not whether it’s going to be dramatically reduced in its importance in Americans’ lives, the question is how much it’s going to cost to do it.”

The Senate bill — sponsored by Homeland Security and Governmental Affairs Chairman Joe Lieberman (I-Conn.) and ranking member Susan Collins (R-Maine) — is expected to set up a process to close post offices and cut back service. The House also is expected to move a bill this summer that would create a panel to implement reforms. But the Senate wants to act before May 15, which is the end of a moratorium for closing post offices and processing centers. A final vote could come as early as this week.

In addition to states with elderly populations, the debate also has pitted states with more urban areas against rural states where delivering the mail can be more expensive.

Sen. Max Baucus (D-Mont.), chairman of the Finance Committee, said it’s a matter of fairness.

Baucus wants a bill that “does not discriminate against rural America,” he said. “There are a lot of ways to help support the post office, but you can’t do it on the backs of rural America.”

Baucus on Tuesday voted against a procedural motion that allowed the Senate to take up the measure. He was one of the four Democrats to do so, but the bill garnered 74 votes to overcome a threatened filibuster.

Baucus is supporting an amendment being offered by Sen. Jeff Merkley (D-Ore.) that would create a two-year moratorium on closing post offices. The amendment also would establish conditions for closing post offices, such as ensuring that seniors and persons with disabilities receive the same or substantially similar service. Also, the economic loss as a result of the closure would not be allowed to exceed the savings to the Postal Service.

Sen. Joe Manchin (D-W.Va.), who also voted against ending debate Monday, offered an amendment that would place a straight two-year moratorium on closing post offices.

He also recommended that the USPS look to make cuts elsewhere including eliminating bonuses for Postal Service executives and ending USPS sponsorships of the U.S. Tour de France team and a NASCAR team, among others.

“I have heard from hundreds of constituents expressing the very same concern: They want their post offices to stay open,” Manchin said. “Private companies won’t step in if the government leaves, and that will simply disconnect our rural communities from the rest of this great nation.”