WASHINGTON (AP) — The Bush administration plans to use its authority to bypass more than 30 laws and regulations in an effort to finish building 670 miles of fence along the southwest U.S. border by the end of this year, federal officials said Tuesday.

Invoking the two legal waivers — which Congress authorized — would cut through bureaucratic red tape and sidestep environmental laws that currently stand in the way of the Homeland Security Department building 267 miles of fencing in California, Arizona, New Mexico and Texas, according to officials familiar with the plan. The officials spoke on condition of anonymity because the waivers had not yet been announced.

The move would be the biggest use of legal waivers since the administration started building the fence, and it would cover a total of 470 miles along the Southwest border. Previously, the department has used its waiver authority for two portions of fence in Arizona and one portion in San Diego.

As of March 17, there were 309 miles of fencing in place, leaving 361 to be completed by the end of the year to meet the department’s goal. Of those, 267 miles are being held up by federal, state and local laws and regulations, the officials said.

One waiver would address the construction of a 22-mile levee barrier in Hidalgo County, Texas. The other waiver would cover 30 miles of fencing and technology deployment on environmentally sensitive ground in San Diego, southern Arizona and the Rio Grande; and 215 miles in California, Arizona and Texas that face other legal impediments due to administrative processes. For instance, building in some areas requires assessments and studies that — if conducted — could not be completed in time to finish the fence by the end of the year.

Homeland Security Secretary Michael Chertoff had said using the waivers would be a last resort. The department has held more than 100 meetings with lawmakers, environmental groups and residents in an effort to work out obstacles and objections to fence construction. The department will conduct environmental assessments when necessary, one of the officials said. But the waivers allow the department to start building before completing the assessments.

The department was expected to announce the plans later Tuesday.

Residents and property owners along the U.S.-Mexico border have complained about the construction of fencing. In South Texas, where opposition has been widespread, land owners refused to give the government access to property along the fence route.

The government has since sued more than 50 property owners in South Texas to gain access to the land.

Environmentalists have also complained about the fence because they say it puts already endangered species such as two types of wild cats — the ocelot and the jaguarundi — in even more danger of extinction. They say the fence would prevent them from swimming across the Rio Grande to mate.

Chertoff has said the fence is good for the environment because immigrants degrade the land with trash and human waste when they sneak illegally into the country.