The Senate approved a bill in April that would, among other things, stretch out payments that the agency has to make into its health care fund for future retirees over 40 years, lowering the annual payment to about $2.5 billion. The Senate bill would also return $11 billion that the Postal Service overpaid into one of its pension funds.

But the House has not taken up its version of the measure, and it is not likely to come up for a vote before lawmakers break for the August recess. That means that any changes in the agency could be delayed until a lame-duck session of Congress after the November elections or even until next year.

The lack of House action has been harshly criticized by senators and mailing industry representatives. “The longer the House delays consideration of the bill, the longer the uncertainty about the Postal Service’s financial future remains,” said Senator Scott Brown, Republican of Massachusetts, one of the co-sponsors of the Senate postal bill. “This is irresponsible and unfair.”

The delay comes as the House has also stopped work on its version of the farm bill, another piece of legislation that the Senate has passed but that House leaders have shown no interest in bringing to a vote. The current farm bill expires on Sept. 30.

Both pieces of legislation have drawn considerable opposition from conservative lawmakers, who want deeper cuts in government spending and who could derail any vote. Democrats in the House also oppose the Postal Service bill because they believe it would worsen the agency’s condition.