First the administration flipped, then it flopped, and now there's a flap over a White House reversal on a key amendment that would water down the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA).

Pressed by the chemical industry and House Republicans led by Rep. William M. Thomas (R-Calif.), the White House has dropped its longstanding opposition to an amendment widely viewed as limiting states' powers to regulate dangerous chemicals.

The Environmental Protection Agency continues to think the states should have the additional powers, although the EPA is barred by the Office of Management and Budget from saying so openly.

And the OMB has added another twist. It has instructed the EPA to drop its once-neutral stance and oppose another pending amendment, offered by Rep. Leon E. Panetta (D-Calif.), that would allow citizens to sue in federal courts over pesticide misuse.

The House is scheduled to vote sometime next week on the FIFRA revisions, which were crafted by the House Agriculture Committee. GOP members are counting on the administration's flip-flop to defeat a proposal by Rep. Tom Harkin (D-Iowa) to leave the state-powers section of current law intact.

Present law gives states the power to require chemical companies to provide more registration data than the federal government requires, if the states have concerns about public safety.

For months the administration had held to the view that the provision should be left alone, in keeping with its philosophy of granting states wider discretion in regulatory matters.

The National Governors Association, the Southern Governors Association and state agriculture departments cheered. Environmental and labor groups cheered. So did Rep. George E. Brown Jr. (D-Calif.), chairman of the Agriculture subcommittee that overrode him and approved limits on states.

But chemical companies booed. They were mad at California, which they claimed had cost them millions of dollars in sales because of delays in registering chemicals. They argued that other states were getting ready to do the same thing, although none has.

As recently as July 19, the president's office informed the House that the Agriculture Committee's weakening of present law was "contrary to administration policy and would unduly and inappropriately preempt state law."

But industry, headed by the Chemical Specialty Manufacturers Association, and House Republicans did not give up. They kept goading the OMB to take another look at the states' rights issue.

On July 23, OMB sent a new position paper to Capitol Hill. Its opposition to the change had vanished. The OMB complained only about a $12 million increase in the FIFRA spending authorization.

OMB spokesmen denied the switch in positions, even though some House Republicans and the chemical manufacturers' group had been told about it, until this week. Then the OMB acknowledged the flip, the flop and the flap.

"We were in error. It was a mixup," said OMB spokesman Edwin L. Dale Jr., explaining the agency's nearly overnight change after holding firm since last year. "I can't deny there has been a change. Now we are neutral on Section 11 the states' rights section . But it always has been a close call."

Dale acknowledged that cajoling by congressional Republicans played a big part in convincing the OMB of the error of its earlier ways.

Thomas, who represents a major farming area that makes heavy use of chemicals regulated by FIFRA, did not mind taking credit for helping the OMB change its mind. He said he talked to the White House, to the OMB and maybe, although he said he didn't recall clearly, to OMB Director David A. Stockman.

"I just had a general conversation about knee-jerk philosophy," Thomas said. He noted that the administration's line has been that the states should share more power with Uncle Sam and do more for themselves.

But California has exasperated the chemical companies with its demands for registration data on their pesticides. And while Thomas says he thinks the concept of states' rights is just fine, he also says his home state is abusing it.

"More states are capable of doing a lot of things, but a lot of them do unreasonable things," he said. "California is the only state that functions above FIFRA. We still have a republic of 50 states, but one of California's problems is that it thinks it is sovereign. It is not the sovereign government of California."