WASHINGTON (AP) - It was Congress' version of "the dog ate my homework."

An entire 34-page section of the farm bill vanished without a trace on its way to becoming law, and red-faced House Democrats gave the reason: No one proofread the parchment it was printed on.

"OK, so we made a mistake," said Rep. Steny H. Hoyer, D-Md., the majority leader. "The bill was not whole."

Republicans cried foul, calling for an investigation.

"We talk to school groups (about) how a bill becomes a law. This is not the way it is done," fumed Rep. David Dreier, R-Calif.

House Speaker Nancy Pelosi, D-Calif., was livid, too.

"Uncustomarily crude," she said of her reaction upon learning of the foul-up, declining to elaborate.

It wasn't exactly a constitutional crisis - or even a juicy conspiracy. Just an embarrassing mistake that could take weeks to correct, and one that marred what should have been a triumphant victory over President Bush for Democrats.

It meant that most - but not all - of the $290 billion agriculture measure Congress meant to pass was enacted Thursday after both the House and Senate resoundingly overrode Bush's veto. The missing section, on trade and international food aid, had cleared Congress, but apparently got lost in the shuffle when House staff aides performed the antiquated ritual of printing out the legislation on heavy parchment paper to be sent to the White House.

Things started going awry Tuesday, as staffers scrambled to complete the bill - called "enrolling" - so it could be signed by the House speaker and Senate president pro tempore and sent to the White House.

House leaders - eager to complete the popular farm bill and override Bush before Congress adjourned for a weeklong Memorial Day break - were pressuring the staff to go faster. In a memo about the mistake obtained by The Associated Press, Lorraine C. Miller, the House clerk, said the enrolling staff reported receiving direct calls from leaders and the Agriculture Committee urging them to hurry.

When it came time to print the legislation, one of the bill's 15 titles never made it onto parchment. The clerk in charge of poring over the final version - known as the enrolling clerk - apparently did not notice the omission.

Such errors - albeit not of this size - happen all the time. One possible reason for this week's goof: Congressional staff aides stopped proofreading the parchment copies of legislation a decade ago, citing the high cost of the paper.

That policy "has been rescinded effective immediately," Miller told congressional leaders in the memo. "We are working diligently to make sure it will not happen again."

"This happens more times than I would like to admit," said Robert B. Dove, a former Senate parliamentarian. "You don't want to see how sausage is made, and you definitely don't want to see how laws are made."

Dove should know. In 1986, he said he secretly agreed to re-enroll and essentially re-enact a massive spending bill that Ronald Reagan had signed and was already the law of the land.

Staff aides discovered that the part of the measure to pay for lighting and heating government buildings had never made it to the White House, and Congress had already adjourned for the year, with Election Day just one week away. Staff quietly prepared a complete copy of the bill, had House and Senate leaders sign it and sent it to Reagan for a second signature.

"Nobody picked up on it, and I never told anyone," Dove said. "It was, to me, the best of a miserable situation."

But it probably wasn't constitutional. "You don't get two chances" to enact the same bill, he said.