A coalition of environmental, labor and trucking industry groups are trying to block a decision by the president to allow Mexican trucks onto U.S. highways, according to media reports.

The group - which includes Public Citizen, the Environmental Law Foundation, the International Brotherhood of Teamsters, the California Federation of Labor AFL-CIO and the California Trucking Association - has asked for a stay from the 9th U.S. Circuit Court of Appeals, The Associated Press reported Dec. 3. The government has until Wednesday to respond.

Last week, President Bush announced the government would open U.S. highways beyond the current 20-mile commercial border zones to Mexican trucks.

The coalition first filed a suit in May, according to Reuters news service. In that action, they claimed the administration skirted environmental laws in considering whether it would allow Mexican trucks to operate beyond the narrow commercial zones. The suit was heard in October, but the court had not ruled as of last Wednesday, when Bush's decision was made public.

A ruling on the request for an emergency stay is expected in the next couple of days, AP said. If the stay isn't granted, trucks could be traveling on U.S. highways as soon as this month.

So far, the Department of Transportation has received about 135 applications from carriers and bus companies based in Mexico seeking to haul their cargo farther into the United States. In addition to those, 854 Mexico-domiciled motor carriers have applied to the FMCSA for provisional certificates of registration to operate in the border commercial zones. Of these 854 applicants, the FMCSA has issued provisional certificates to 459.

The petition for an emergency stay requested a full environmental review of how older-model, diesel-powered Mexican trucks would affect air quality, Reuters reported. In making its decision to allow the trucks, the government found they would have "no significant impact" on the environment. And Transportation Secretary Norman Mineta has said that Mexican trucks would be held to the same standards as U.S. operators.

However, the coalition asking for the emergency stay said the decision would let high-pollution vehicles into the country, violating clean air requirements. Al Meyerhoff, an attorney for the groups, said more than half the Mexican trucks were made before 1994, when there were fewer regulations on their emissions.