The Environmental Protection Agency, which announced this summer that it would halt work at dozens of toxic-waste dumps lest it run out of funds before Congress renews the Superfund cleanup law, now is lobbying the Senate not to let it collect money for the program for another seven weeks.

The taxing mechanism that finances Superfund expired when the fiscal year ended Sept. 30. In an effort to keep the money rolling in while Congress completes work on a new five-year reauthorization of the law, the House last week approved a 45-day extension of the tax, which is levied on petroleum and raw chemical materials and brings in about $750,000 a day.

But in a letter this week to Majority Leader Robert J. Dole (R-Kan.), EPA Administrator Lee M. Thomas urged the Senate not to pass the "ill-advised" extension, saying it "would have no positive effect on cleaning up any more sites."

At the root of this confusing line of reasoning is not finances, but politics.

The argument that Superfund either is, or is not, flat-busted has been made on both sides of the debate at one time or another, depending on whether they were seeking to speed up or slow down the movement of the various bills to renew it.

EPA and state officials privately acknowledge that the cleanup situation is not so dire as the agency portrayed it this summer when it announced its work slowdown. For one thing, funds usually are obligated months and even years before they actually are spent. But the same officials say a 45-day extension probably is not much of a salvation, either. Because Superfund tax collections are made quarterly, the money would not be collected until the end of the calendar quarter, on Dec. 31.

EPA's current interest in maintaining the image of a dormant program stems from the administration's desire to see a Superfund bill enacted this year rather than in the heat of an election year. Last year, the Democratic-controlled House passed an ambitious Superfund measure that died in the Republican-controlled Senate.

This year, the Senate already has passed its bill. Although the $7.5 billion measure is almost 50 percent bigger than President Reagan wants, and would be funded by a broad-based tax that the White House despises, the administration considers it a better alternative than the House's $10.1 billion version.

In the House, Superfund legislation still is wending its way through multiple committees. Democrats are bitterly divided over the shape of the bill, several rival measures have surfaced and some lawmakers already have advanced the idea of a one-year extension of Superfund.

All of the House proposals would be in the range of $10 billion, but there are critical differences in the bills in the areas of liability, cleanup deadlines and community and citizen rights.

The 45-day extension basically was pushed by a group of Democrats who oppose a bill reported out by the Energy and Commerce Committee and needed more time to fashion an alternative.

The Public Works and Transportation Committee is expected to approve that alternative today, leaving just one committee between Superfund and the House floor. That is the Ways and Means Committee, which has to devise a way to pay for the program.

In the Senate, meanwhile, the funding extension appears to be going nowhere. In comments on the floor last week, Dole said he was not inclined to bring it to the floor and wished the House would just pass a Superfund bill instead.

RCRA ROULETTE . . . While the White House and Congress wrangle over Superfund, the EPA and the Office of Management and Budget are playing their own version of chicken over the hazardous-waste disposal law.

Last July, the EPA sent OMB a set of rules designed to make it easier for states to keep up with a welter of regulatory deadlines in the Resource Conservation and Recovery Act as amended by Congress last year. The rules essentially would let states update their own rules once a year, rather than each time the EPA issues a standard under the law's new deadlines.

OMB has held up the rules because it wants the states to pick up the program more quickly, reducing the drain on federal resources.

The problem, according to EPA officials, is that if the rules are not out by Nov. 8, more than a dozen states will have to start turning enforcement of the waste-disposal law back to the federal government.

That can get expensive, as was demonstrated when Iowa was forced to turn the program back this summer. Iowa had been handling the program with a $200,000 grant, with which it hired 18 people. The EPA was able to hire only six contractors for the same money and had to beef up its regional headquarters in Kansas City with a dozen more employes.