EPA Administrator Christine Todd Whitman will meet with the lawmaker group, headed by Rep. Ray LaHood, whose Peoria, Illinois, district is the home to giant diesel engine maker Caterpillar Inc. .

The new standards could have "devastating consequences" for U.S. truck makers if it goes into effect in October, the GOP lawmakers wrote in a letter sent to Whitman on June 28.

"Unless our trucking industry is given lead time to field and test new equipment, they will not purchase these new engines, resulting in thousands of layoffs across the country," lawmakers warned in the letter.

The letter is an indication that the new EPA diesel rules are "under attack" by U.S. industry and some U.S. lawmakers, said Bill Becker at the State and Territorial Air Pollution Program Administrators.

An EPA spokesman warned against reading sinister purposes into the meeting. "It's in the court's hands to decide the next step" on the diesel rules, said spokesman Joe Martyak. "In the interim here our intention is staying the course." He confirmed that Whitman will meet with the lawmakers, possibly on Thursday.

The American Trucking Association and Caterpillar are an "axle of evil" pursuing an "all-out political attack on the new standards," said Frank O'Donnell at the Clean Air Trust.

The ATA on June 27 petitioned President George W. Bush to delay the new rules on grounds that modifications could add nearly $9,000 to the price tag of new truck engines, a ten-fold increase from EPA's original $803 cost increase estimate.

The EPA rules, unveiled in the waning days of the Clinton administration and later affirmed by the Bush administration, will force firms to produce cleaner-burning diesel engines, and compel refiners to make the fuel for them.

A potential congressional rider rumored to be in the works could weaken noncompliance penalties in the EPA rule, Becker said. There are also potential legislative plans to divert noncompliance penalties to a fund to give tax credits for engine makers that cannot comply with new rules, he said.

"Any number of those riders could weaken or undermine this whole effort," he said.

Lawmakers met with EPA and Department of Justice officials in June to discuss noncompliance penalties in a session attended by staffers with House Speaker Dennis Hastert, an Illinois Republican, according to public EPA documents.

The new fuel will go into use in mid-2006, and auto makers are expected to begin rolling out new models next year to burn the new gasoline in 2004.

The standard requires diesel engines to cut particulates and nitrogen oxides by over 90 percent.

The EPA has estimated the rule could prevent 8,300 premature deaths annually, thousands of cases of bronchitis and other respiratory ailments, and cost about $4 billion a year to implement.