A small group of postal workers and supporters began a four-day hunger strike Monday to protest the U.S. Postal Service’s deteriorating finances and service and Congress’s failure to address the situation.

The 10 strikers will make their stand days before the postal service makes changes that will end overnight delivery of up to 20 percent of first-class mail, as mail-sorting hubs are shuttered.

The group, Communities and Postal Workers United, was formed this spring.

Rep. Dennis Kucinich (D-Ohio) led Monday’s rally in front of the U.S. Capitol. In a speech, he asked Congress to end prefunding of health benefits, which is sapping more than $5 billion from the postal service’s ledger.

“I will continue to fight any efforts to weaken the Postal Service, including any efforts to privatize essential services,” Kucinich said. “There are ways to generate revenue without cutting jobs, essential services and closing vital post office branches in communities that rely on them.”

On Tuesday, the activists will march to the Capitol from the postal service headquarters at L’Enfant Plaza; on Wednesday, they plan a protest outside The Washington Post offices on 15th Street NW. The strike is set to end Thursday with a rally in front of USPS headquarters, where they said they’ll try to meet with Postmaster General Patrick Donahoe.

The activists said they are protesting series of Post editorials that support more cost-cutting and criticize USPS labor contracts as too generous to workers.

But the biggest target is Congress, which has not passed reform legislation. The Senate approved a bill in April that would rebalance postal finances by giving billions of dollars to offer buyouts and early retirement incentives to employees. Several bills are pending in the House.

The shirts activists plan to wear will read: “Congress is starving the postal service.”

The theme of the strike is that cuts to service — slower mail, reduced window hours at 13,000 rural post offices, shuttering processing plants — will only hurt business by draining revenue. There’s a labor issue too: The service is expected to lose tens of thousands of jobs in coming years through buyouts and attrition.

“You reduce service, and people give up on the service,” said Jamie Partridge, a retired letter carrier from Portland who is coming to Washington to strike. “It’s a self-fulfilling prophecy.”

Activists said declining mail volume and union contracts are not the cause of financial woes. Congress, they said, can solve the problem by giving the postal service access funds it has paid into health benefit and pension funds.

Among those is a 2006 law that required USPS to prefund retiree health benefits through 2016 — at more than $5 billion a year.

Also, it has overfunded its federal pension obligations by nearly 105 percent, or $13.5 billion, for the federal fiscal year ending Sept. 30, 2011, according to a report issued Monday by the agency’s inspector general.

“The pension overfunding we absolutely think should be returned to the Postal Service to help them get out of the hole that they’re in and get some stability,” said Sally Davidow, communications director for the American Postal Workers Union.

A provision in the 2012 postal reform act that passed the Senate and is in the House would return the surplus from the Federal Employee Retirement System. That bill also proposes returning all future surpluses to the agency.

A separate postal reform bill introduced in the House would return a $10 billion 2010 FERS surplus within two weeks after passage. Both bills are pending House approval.

The hunger strikers want Donahoe to maintain delivery standards and suspend cuts and closures until Congress acts.

In a statement Friday, the postal service said, “We respect the right of our employees and retirees to engage in lawful public dialogue regarding postal issues. We have worked hard over this past year to bring to the attention of Congress, the [Obama] administration, the news media and the American public the urgent need for postal reform legislation.”

But the statement said the agency’s projected losses of $14 billion this fiscal year require “necessary and responsible cost-reduction steps.”

The protesters have been endorsed by groups in the Occupy movement, as well as local chapters of several postal unions.